Fluid electrolyte changes in trained subjects after water loading and during restriction of muscular activity and chronic hyperhydration

The objective of this investigation was to determine fluid electrolyte changes after water-loading tests and during hypokinesia (decreased number of km taken per day) and daily intake of fluid and salt supplementation (FSS). The studies during hypokinesia (HK) were performed for 364 d on 30 endurance-trained male volunteers in the age range of 23–26 yr, with an average peak oxygen uptake, POU, of 64 mL/kg/min. All volunteers were divided into three equal groups: 10 volunteers were placed on a continuous regime of exercise of 14.4 km/d and served as control subjects (CS); 10 volunteers were submitted to continuous HK without FSS and were considered as the unsupplemented hypokinetic subjects (UHS); and 10 volunteers were under continuous HK and FSS and were considered as the supplemented hypokinetic subjects (SHS). For the simulation of the hypokinetic effect, the UHS and SHS groups were kept continuously under an average of 2.7 km/d for the duration of the study. Prior to exposure to HK, the two groups of volunteers were on the same exercise regime as the control group. During a 60-d preexperimental period and during the remainder of the study, water-loading tests with a water load of 20 mL/kg body wt/min were performed, and urinary and plasma electrolytes (sodium, potassium, calcium, and magnesium) were measured. In the SHS group, urinary excretion of electrolytes and plasma electrolyte content decreased, while in the UHS these values increased after water loading tests and during HK. Based on the obtained data, it is concluded that chronic hyperhydration may be used to prevent or minimize urinary and plasma electrolyte changes in endurance-trained volunteers after water-loading tests and during prolonged restriction of muscular activity.     

Effect of daily hyperhydration on fluid-electrolyte changes in endurance-trained volunteers during prolonged restriction of muscular activity

The aim of this investigation was to evaluate the effect of a daily intake of fluid and salt supplementation on fluid and electrolyte losses in endurance-trained volunteers during prolonged restriction of muscular activity (hypokinesia). The studies were performed on 30 long-distance runners aged 23–26 who had a peak oxygen uptake of 65.5 mL/kg/min and had taken 13.8 km/d on average prior to their participation in the study. The volunteers were divided into three groups: The volunteers in the first group were placed under normal ambulatory conditions (control subjects), the second group of volunteers subjected to hypokinesia alone (hypokinetic subjects), and the third group of volunteers was submitted to HK and consumed daily 0.1 g sodium chloride (NaCl)/kg body wt and 26 mL water/kg body wt (hyperhydrated subjects). The second and third group of volunteers were kept under an average of 2.7 km/d for 364 d. During the pre-experimental period of 60 d and during the experimental period of 364 d sodium, potassium, calcium, and magnesium in urine and plasma were determined. Blood was also assayed for osmolality, hemoglobin, hematocrit, plasma volume, plasma renin activity and plasma aldosterone. Mean arterial blood pressure was also determined. In the hyperhydrated volunteers plasma volume and arterial blood pressure increased, whereas plasma osmolality, plasma renin activity, plasma aldosterone, hematocrit, hemoglobin concentration, and urinary excretion and concentrations of electrolytes in plasma decreased. In the hypokinetic volunteers, plasma volume and arterial blood pressure decreased significantly, whereas hematocrit values, hemoglobin concenfration, plasma osmolality, plasma renin activity, plasma aldosterone, and electrolytes in urine and plasma increased significantly during the experimental period. It was concluded that chronic hyperhydration may be used in minimizing fluid and electrolyte losses in endurance-trained volunteers during prolonged restriction of muscular activity.     

Potassium loading effect on potassium balance in athletes during prolonged restriction of muscular activity

Negative potassium balance during hypokinesia (decreased number of kilometers taken/day) is not based on the potassium shortage in the diet, but on the impossibility of the body to retain potassium. To assess this hypothesis, we study the effect of potassium loading on athletes during prolonged hypokinesia (HK). Studies were done during 30 d of a pre-HK period and during 364 d of an HK period. Forty male athletes aged 23–26 yr were chosen as subjects. They were divided equally into four groups: unloaded ambulatory control subjects (UACS), unloaded hypokinetic subjects (UHKS), loaded hypokinetic subjects (LHKS), and loaded ambulatory control subjects (LACS). For the simulation of the hypokinetic effect, the LHKS and UHKS groups were kept under an average running distance of 1.7 km/d. In the LACS and LHKS groups, potassium loading tests were done by administering 95.35 mg KC1 per kg body weight. During the pre-HK and HK periods and after KC1 loading tests, fecal and urinary potassium excretion, sodium and chloride excretion, plasma potassium, sodium and chloride concentration, and potassium balance were measured. Plasma renin activity (PRA) and plasma aldosterone concentration was also measured. Negative potassium balance increased significantly (p < -0.01) in the UHKS and LHKS groups when compared with the UACS and LACS groups. Plasma electrolyte concentration, urinary electrolyte excretion, fecal potassium excretion, PRA, and PA concentration increased significantly (p ≤ 0.01) in the LHKS and UHKS groups when compared with LACS and UACS groups. Urinary and fecal potassium excretion increased much more and much faster in the LHKS group than in the UHKS group. By contrast, the corresponding parameters change insignificantly in the UACS and LACS groups when compared with the base line control values. It was concluded that urinary and fecal potassium excretion increased significantly despite the presence of negative potassium balance; thus, negative potassium balance may not be based on potassium shortage in the diet because of the impossibility of the body to retain potassium during HK.     

Daily hyperhydration effect on electrolyte deficiency of endurance-Trained subjects during prolonged hypokinesia

The aim of this study was to evaluate the effect of a daily intake of fluid and salt supplementation (FSS) on the deficiency of electrolytes, which is characterized by higher rather than lower plasma concentration of electrolytes during prolonged hypokinesia (HK) (decreased number of km taken per day). Forty long distance runners aged 22–25 yr with a peak V0₂ 65.4 mL min^-1 kg^-1 with an average 14.2 km d running distance were selected as subjects. They were equally divided into four groups: 1) unsupplemented control subjects (UCS); 2) unsupplemented hypokinetic subjects (UHS); 3) supplemented hypokinetic subjects (SHS), and 4) supplemented control subjects (SCS). During the investigation of 364 d, groups 2 and 3 maintained an average running distance of less than 4.7 km per day, groups 1 and 4 did not experience any modification in their normal training routines and diets. During the preexperimental period of 60 d and during the experimental period of 364 d urinary excretion of electrolytes and concentrations of sodium, potassium, calcium, and magnesium in plasma were determined. Whole blood hemoglobin, hematocrit index, plasma osmolality, and plasma protein concentration were measured. In the UHS plasma concentration of electrolytes and urinary excretion thereof, fluid elimination, hematocrit, whole blood hemoglobin, plasma osmolality, and plasma protein concentration increased significantly (p < 0.05) when compared with the UCS, SCS, and SHS groups. In the SHS plasma concentration of electrolytes and urinary excretion thereof, fluid excretion, whole blood hemoglobin, hematocrit, plasma osmolality, and plasma protein concentration decreased when compared with the UHS and increased insignificantly when compared with the UCS and SCS groups. It was concluded that FSS may be used to prevent or minimize electrolyte deficiency in endurance-trained volunteers during prolonged restriction of muscular activity.     

Daily copper supplement effects on copper balance in trained subjects during prolonged restriction of muscular activity

The aim of this study was to assess the effect of a daily intake of copper supplements on negative copper balance during prolonged exposure to hypokinesia (decreased number of kilometers per day). During hypokinesia (HK), negative copper balance is shown by increased, not by decreased, serum copper concentration, as it happens in other situations. Studies were done during a 30-d prehypokinetic period and a 364-d hypokinetic period. Forty male trained volunteers aged 22–26 yr with a peak oxygen uptake of 66.4 mL/min/kg and with an average of 13.7 km/d running distance were chosen as subjects. They were equally divided into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS), and supplemented ambulatory control subjects (SACS). The SACS and SHKS groups took 0.09 mg copper carbonate/kg body weight daily. The SHKS and UHKS groups were maintained under an average running distance of 1.7 km/d, whereas the SACS and UACS groups did not experience any modifications in their normal training routines. During the 30-d prehypokinetic period and the 346-d hypokinetic period, urinary excretion of copper, calcium, and magnesium and serum concentrations of copper, calcium, and magnesium were measured. Copper loss in feces and copper balance was also determined. In both UHKS and SHKS groups, urinary excretion of copper, calcium, and magnesium and concentrations of copper, magnesium, and calcium in serum increased significantly when compared with the SACS and UACS groups. Loss of copper in feces was also increased significantly in the SHKS and UHKS groups when compared with the UACS and SACS groups. Throughout the study, the copper balance was negative in the SHKS and UHKS groups, whereas in the SACS and UACS groups, the copper balance was positive. It was concluded that a daily intake of copper supplements cannot be used to prevent copper deficiency shown by increased copper concentration. Copper supplements also failed to prevent negative copper balance and copper losses in feces and urine in endurancetrained subjects during prolonged exposure to HK.     

Blood plasma concentrations of microelements in endurance trained volunteers during hypokinesia and chronic hyperhydration

The objective of this investigation was to determine the effect of daily intake of fluid and salt supplementation (FSS) on increased urinary losses of microelements that developed during hypokinesia (decreased number of walking steps/d). The studies were performed on 30 endurance-trained male volunteers aged 23–26 yr, with an averaged maximum oxygen uptake of 65 mL/kg/min during 364 d of hypokinesia (HK). All volunteers were divided into three equal groups: Ten volunteers were placed continuously under an average of 10,000 running steps/d (14.2 km/d) (control subjects), ten volunteers subjected continuously to HK without the use of FSS (hypokinetic subjects), and ten volunteers were continuously submitted to HK and consumed daily FSS (hyperhydrated subjects). For the simulation of the hypokinetic effect the hypokinetic and hyperhydrated volunteers were kept under an average of 3,000 walking steps/d (2.7 km/d) for 364 d. Prior to their exposure to HK the volunteers were on an average of 10,000 running steps/d (14.2 km/d). During the prehypokinetic period of 60 d and during the hypokinetic period of 364 d were determined renal excretion of microelements responses of endurance-trained volunteers. In the hyperhydrated volunteers urinary excretion of iron, zinc, copper, manganese, cobalt, nickel, lead, tin, chromium, aluminum, molybdenum, and vanadium decreased, whereas in the hypokinetic volunteers it increased significantly. It was concluded that chronic hyperhydration may be used to attenuate urinary excretion of microelements in endurance-trained volunteers during prolonged restriction of muscular activity.     

Magnesium loading effect on magnesium deficiency in endurance-trained subjects during prolonged restriction of muscular activity

The aim of this study was to evaluate the effect of magnesium (Mg) loading (10.0 mg Mg/kg body wt) and daily Mg supplements (5.0 mg Mg/kg body wt) on Mg deficiency shown by increased and not by decreased serum Mg concentration during hypokinesia (decreased km number/d). The studies were done during 30 d of prehypokinesia and 364 d of hypokinesia (HK) periods. Forty endurance-trained volunteers aged 22–26 yr with a peak VO2 max of 66.3 mL·kg⁻¹ min⁻¹ and with an average 15.0 km/d running distance were chose as subjects. They were equally divided into four groups:

Plasma trace elements concentrations in trained subjects after exposure to hypokinesia and daily hyperhydration

The objective of this investigation was to evaluate the effect of a daily intake of fluid and salt supplementation (FSS) on blood plasma trace elements concentrations in physically healthy volunteers after exposure to 364 d of hypokinesia (decreased number of steps per day). The studies were performed after exposure to 364 d of Hypokinesia (HK) on 30 long-distance runners of volunteers who had a VO₂ max 67 mL/kg/min and were ranging in the age of 19–24 yrs. Prior to their exposure to HK all volunteers were on an average of 10,000 steps/d. For the simulation of the hypokinetic effect the volunteers were kept under an average of 3000 steps/d. All volunteers were divided into three equal groups. The first group of volunteers subjected to HK and received daily FSS (water 26 mL/kg body wt and sodium chloride 0.16 g/kg body wt.), the second groups of volunteers submitted only to HK, and the third group of volunteers underwent a normal ambulatory life and served as control. The content of manganese, calcium, magnesium, iron, lead, copper, tin, nickel, zinc and cobalamine were determined in blood plasma of volunteers. By the end of the hypokinetic period the blood plasma concentration of microelements increased significantly in the hypokinetic subjects (second group), whereas in the hyperhydrated subjects (first group) decreased. It was concluded that prolonged restriction of motor activity induced significant increases in blood trace elements concentrations whereas daily hyperhydration had a normalizing effect on their concentration in blood plasma. This indicates that daily hyperhydration may be used to normalize blood plasma concentrations of microelements in physically healthy volunteers subjected to prolonged restriction of motor activity.     

Calcium loading and renal function in trained subjects during restriction of muscular activity and chronic hyperhydration

It was suggested that negative calcium balance is not based on the shortage of calcium in the diet, but on the decreased tissular capacity of the body to retain calcium during hypokinesia (decreased muscular activity), and that chronic hyperhydration may be used to normalize calcium balance. To evaluate this hypothesis studies were performed on 30 long distance runners aged 23–26 yr, with an average maximum oxygen uptake 65 mL/kg/min during 364 d of hypokinesia (HK). All volunteers were divided into three equal groups: Ten volunteers were placed continuously under an average of 14.9 km/d (control subjects), ten volunteers were subjected continuously to HK (hypokinetic subjects), and ten volunteers were submitted continuously to HK with daily consumption of an additional amount of 26 mL water/kg body wt and 0.16 g sodium chloride (NaCl)/kg body wt (hyperhydrated subjects). For the simulation of the hypokinetic effect, the hypokinetic and hyperhydrated volunteers were kept under an average of 2.7 km/day for 364 d. During the prehypokinetic period and hypokinetic period calcium lactate loading tests (0.55 mEq/kg body wt) were performed. Urinary and blood electrolytes (sodium, ionized calcium, total calcium, magnesium, and phosphate) and blood parathyroid hormone (PTH) were determined. Urinary electrolytes and concentrations in blood thereof decreased in the hyperhydrated and increased significantly in the hypokinetic volunteers. Blood parathyroid hormone content increased in the hyperhydrated and decreased in the hypokinetic volunteers. After calcium lactate loading tests, the hypokinetic volunteers displayed a faster excretion of calcium and a decreased blood PTH content as compared to the control and hyperhydrated groups of volunteers. It was concluded that calcium deficiency during HK is associated with decreased tissular capacity of the body to retain calcium, whereas chronic hyperhydration may be used to prevent calcium deficiency in endurance trained volunteers during prolonged restriction of muscular activity.     

Zinc metabolism in endurance-trained volunteers during prolonged restriction of muscular activity and chronic hyperhydration

The objective of this study was to evaluate the effects of hypokinesia (HK) and fluid- and salt supplementation (FSS) on zinc metabolism in endurance-trained volunteers (ETV) for a period of 364 d. Thirty long-distance runners aged 22–25 yr with a peak V_O2 of 67 mL/min/kg with an average 13.8 km/d running distance were chosen as subjects. They were equally divided into three groups:

Phosphate-loading tests influences on endurance-trained volunteers during restriction of muscular activity and chronic hyperhydration

The purpose of this investigation was to determine whether negative phosphate balance, which is developed during hypokinesia (a decreased number of walking steps/d) could be reversed with daily supplementation with phosphate, fluid, and salt (FSS). The studies on hypokinesia (HK) were performed for 364 d on 30 endurance-trained male volunteers in the age range of 23–26 yr, with an average maximum oxygen uptake, MOU, of 65 mL/kg min. All subjects were divided into three equal groups: Ten volunteers were placed on a continuous regime of exercise of 14.4 kmJd at 10,000 steps/d and served as controls. Ten volunteers were subject to continuous HK without FSS and were considered as the hypokinetic subjects (HS). The remaining subjects were under continuous HK and FSS and were considered as the hypokinetic, hyperhydrated subjects (HHS). The three groups were on a diet that averaged 2620 cal/d and contained 1.7 g calcium, 1.6 g phosphate, and 5.6 g sodium chloride. For simulation of the hypokinetic effect, the HS and HHS groups were kept continuously under 2.9 km/d (3000 walking steps/d) for the duration of the study. Prior to exposure to HK, all volunteers were on the same exercise regime as the controls. During a 60-d pre-HK period and during the remainder of the study, phosphate-loading tests, urinary and plasma phosphate concentrations were performed in all subjects. In the HHS group, plasma phosphate concentration and urinary excretion of phosphate were decreased, while in the HS group these values increased after phosphate loading. Based on our results, we concluded that chronic hyperhydration and phosphate supplementation may be used to minimize phosphate losses in endurance-trained volunteers during prolonged restriction of muscular activity.     

Phosphate determination during hypokinesia and ambulation in establishing phosphate changes in trained and untrained subjects

Hypokinesia (diminished movement) induces phosphate (P) changes; however, it is not known if P change is greater in trained than untrained subjects. Measuring P balance and P retention during hypokinesia (HK) and P load, we studied if changes in P retention and P depletion were significantly (p<0.05) greater in trained than untrained subjects. Studies were done during a 30-d pre-HK period and a 364-d HK period. Forty male trained and untrained healthy individuals aged 24.5±5.4 yr were chosen as subjects. All volunteers were equally divided into four groups: trained ambulatory control subjects (TACS), trained hypokinetic subjects (THKS), untrained ambulatory control subjects (UACS), and untrained hypokinetic subjects (UHKS). All THKS and UHKS were limited to an average walking distance of 0.3 km/d, and TACS and UACS were on an average running distance of 9.8 and 1.8 km/d, respectively. Subjects took daily 12.7-mmol dicalcium-phosphate/kg body weight in the form of supplementation. Negative P balance, fecal P loss, urinary P and calcium (Ca) excretion, serum P, and total Ca (Ca_t) levels increased significantly (p<0.05), whereas P retention, serum 1,25-dihydroxyvitamin D [1,25 (OH)₂D₃] and intact parathyroid hormone (iPTH) level decreased significantly (p<0.05) in THKS and UHKS when compared with their pre-HK values and their respective ambulatory controls (TACS and UACS). However, P retention, P balance, serum, urinary, and fecal P, and serum hormone level changed significantly (p<0.05) more in THKS than UHKS. Retention of P, fecal P, urinary P and Ca loss, serum P and Ca_t level, P balance, 1,25(OH)₂D₃, and iPTH level change insignificantly (p>0.05) in TACS and UACS when compared with their pre-HK control values. It was concluded that significant negative P balance may indicate P depletion, whereas significant P loss in spite of negative P balance and P load may suggest P retention incapacity; however, P depletion was greater in THKS than UHKS. Clearly, P is wasted much more in THKS than UHKS.     

Serum, urinary, and fecal calcium changes in trained and untrained subjects during prolonged hypokinetic and ambulatory conditions

Electrolyte metabolism undergoes significant changes in trained subjects, but it is unknown if it undergoes significant changes in untrained subjects during hypokinesia (decreased movement). The aim of this study was to measure calcium (Ca) changes in trained and untrained subjects during prolonged hypokinesia (HK). Studies were done during 30 d of a pre-HK period and 364 d of a HK period. Forty male trained and untrained volunteers aged 23–26 yr were chosen as subjects. All subjects were equally divided into four groups: trained ambulatory control subjects (TACS), trained hypokinetic subjects (THKS), untrained hypokinetic subjects (UHKS), and untrained ambulatory control subjects (UACS). The THKS and UHKS groups were kept under an average running distance of 0.7 km/d. Fecal Ca excretion, urinary Ca and magnesium (Mg) excretion, serum ionized calcium (Ca_I), Ca, Mg, intact parathyroid hormone (iPTH) and 1,25 dihydroxyvitamin D [1,25 (OH)2 D] concentration, body weight, and peak oxygen uptake were measured. Fecal Ca loss, urinary Ca and Mg excretion, and serum Ca_I, Mg, and Ca increased significantly (p ≤ 0.01), whereas serum iPTH and 1,25 (OH)2 D concentration body weight and peak oxygen uptake decreased significantly (p ≤ 0.01) in the THKS and UHKS groups when compared with the TACS and UACS groups. The measured parameters were much greater and much faster in the THKS group than in the UHKS group. By contrast, the corresponding parameters did not change significantly in the TACS and UACS groups when compared with the baseline control values. It was concluded that prolonged HK induces significant fecal, urinary, and serum Ca changes in the hypokinetic subjects when compared with control subjects. However, fecal, urinary, and serum Ca changes were much greater and appeared much faster in the THKS group than the UHKS group.     

Urinary and plasma calcium changes in endurance trained volunteers during exposure to acute and rigorous bed rest conditions

The purpose of the present study was to evaluate the effect of acute (abrupt restriction of muscular activity) and rigorous bed-rest conditions on urinary and plasma calcium changes in endurance trained volunteers. The studies were performed on 30 long distance runners ages 23–25 who had a peak oxygen uptake of 66.0 mL/min/kg and had run 14.0 km/d on the average prior to their participation in the study. The volunteers were divided into three groups: The volunteers in the first group were under normal ambulatory conditions (control subjects), the second group was subjected to an acute bed-rest regime (acute bedrested subjects), and the third group was submitted to a rigorous bed-rest regime (rigorous bedrested subjects). The second and third groups of volunteers were kept under a rigorous bed rest regime for 7 d. During the pre-bed-rest period and during the actual bed-rest periods (acute and rigorous bed-rest periods), urinary excretion of calcium and plasma calcium and parathyroid hormone (PTH) concentrations were determined. During the 1st d of acute and rigorous bed-rest periods, urinary excretion and plasma concentration of calcium increased significantly (P≤0.05), while plasma parathyroid hormone content decreased significantly (P≤0.05). On the 3rd d of the experimental period, urinary excretion and plasma calcium concentration decreased somewhat, during the 7th d, calcium in urine and plasma increased further, while parathyroid hormone content in plasma increased somewhat on the 3rd d and decreased again on the 7th d of the experimental period. The changes were more pronounced in the volunteers who were subjected to acute bed-rest conditions than in the volunteers who were submitted to rigorous bed-rest conditions. It was concluded that exposure to acute bed-rest conditions induces significantly greater urinary and serum calcium changes than rigorous bed-rest conditions in endurance trained volunteers.     

Water metabolic parameter changes in rhesus monkeys during exposure to prolonged restriction of motor activity

The objective of this investigation was to determine the effect of prolonged restriction of motor activity (hypokinesia [HK]) on several parameters of water metabolism in primates. The studies were performed on 12 rhesus monkeys aged 4–5 yr (5.10–6.85 kg) during the hypokinetic period of 90 d and during the prehypokinetic period of 30 d. They were divided into two equal groups: the first group was placed under ordinary vivarium conditions (vivarium control animals) and the second group was subjected to 90 d of HK (hypokinetic animals). For the simulation of the hypokinetic effect, the primates were immobilized on their abdomens in special tables. The legs of the monkeys were immobilized with hip and knee joints extended. The primates retained freedom of movement at elbow, wrist, and ankle. During the preexperimental period of 30 d and during the experimental period of 90 d, the following variables were determined: body weight, total body fluid content, specific total body fluid, mean fluid consumed and eliminated in urine, specific plasma resistance, hematocrit level, and plasma concentrations of sodium (Na) and potassium (K). In the hypokinetic primates, body weight decreased significantly when compared to the controls. Mean fluid intake, total body fluid, and specific total body fluid decreased, whereas mean daily fluid loss and specific mean daily fluid elimination increased significantly. Specific plasma resistance, hematocrit level, and plasma electrolyte concentrations increased significantly when compared to the control primates. It was concluded that prolonged restriction of motor activity induces significant changes in water metabolic parameters of primates leading in decreased total water content of the body.     

Potassium content in soil,uptake in plants and the potassium balance in three European long-term field experiments

This study quantitatively assesses the fate of K derived from mineral fertilizers and organic manures and the effective K balance in three long-term field experiments at Rothamsted (UK), Bad Lauchstaedt (Germany) and Skierniewice (Poland). Plant availability, uptake and the overall utilization of K over the last 30 years (1965–1996) are discussed and related to soil K Availability Indices determined by the standard methods used in each of the three countries. In addition, to provide a standard comparison of the three sites, Exchangeable K (1 M NH₄OAc) and Non-exchangeable K (K extracted by boiling with 1 M HNO₃) were measured on one recent (1995) set of soil samples. Plant availability and utilization of K was partly related to clay content, but more closely to the cation exchange surfaces associated with both mineral and organic constituents and also, at Rothamsted, to the capacity of clay minerals to fix K. The recovery rate of K from mineral fertilizer by crops did not exceed 62%. Fertilizers were least effective in the most strongly K fixing soil at Rothamsted (44% maximum) and most effective in the soil with the highest cation exchange capacity (CEC) at Bad Lauchstaedt (62%), where the greater quantity of exchange sites appear to be associated with humic material. Recoveries of K from farmyard manure (FYM) varied from 22–117% (values of >100% indicating subsoil uptake or the release of reserves). Deficiencies of N, P and Mg in some treatments decreased the effectiveness of applied K and may have caused increased leaching of K from the plough layer. FYM was generally more effective than mineral fertilizer where mineral N and P were not applied because these nutrients were effectively supplied in the manure. But the effectiveness of mineral K fertilizer decreased when applied in combination with FYM because FYM was the preferred source of K. Where FYM application increased the CEC of soils, this also improved K utilization but only where K was not extensively leached or fixed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Daily zinc supplementation effect on zinc deficiency in rats during prolonged restriction of motor activity

The objective of this investigation was to evaluate the effect of 47 mg zinc supplementation on deficiency of zinc in rats during 98 d of restriction of motor activity (hypokinesia), which appeared by higher plasma zinc concentration. One Hundred 13-week-old Sprague-Dawley male rats weighing 360–390 g were used to perform the studies: They were equally divided into four groups: 1. Unsupplemented control animals (UCA); 2. Unsupplemented hypokinetic animals (UHA); 3. Supplemented control animals (SCA); and 4. Supplemented hypokinetic animals (SHA). For the simulation of the effect of hypokinesia (HK), the UHA and SHA were kept in small individual cages made of wood, which restricted their movements in all directions without hindering food and water intake. The SCA and SHA received daily with their food an additional amount of zinc. Before and during the experimental period of 98 d, plasma, urinary and fecal zinc, balance of zinc, food intake, and body weight were determined at different intervals. In the SHA and UHA, the concentration of zinc in plasma, and the elimination of zinc in urine and feces increased significantly when compared with the SCA and UCA, whereas the balance of zinc was negative. The body weight and food intake decreased significantly in the SHA and UHA when compared with the SCA and UCA. The increased plasma concentration of zinc in both the SHA and UHA groups was in contrast to the observed hypozincnemia during prolonged immobilization as during prolonged hospitalization. This reaction suggests that there may be some other mechanisms that are affecting the process of control and regulation of zinc metabolism during prolonged HK. It was concluded that exposure to prolonged restriction of motor activity of rats induces significant increases in plasma concentration, fecal and urinary elimination of zinc in the presence of negative zinc balance and regardless the daily intake of large amounts of zinc with their food, leading to zinc deficiency.     

Stimulation of sugar loading into sieve elements of willow by potassium and sodium salts

Potassium as the chloride, nitrate or sulphate or sodium as the chloride, were applied at a concentration of 50 mM either to the xylem of stem segments or to the cambial surface of bark strips of willow. Potassium chloride increased the concentration of sucrose in sieve tube exudate collected via severed aphid stylets, without significantly affecting the volume flow rate, or the concentration of potassium in the exudate. The increase in the sucrose level in the sieve tube sap was shown to be due to a stimulation of loading, rather than to an enhancement of longitudinal transport. Potassium nitrate and sulphate or sodium chloride, were not as effective as potassium chloride in stimulating the loading of sucrose. It is suggested that uptake of the cation into cells supplying sugars to the sieve tube is linked to the rate of release of sugars by the supplying cells.     

Urinary excretion of microelements in endurance-trained volunteers during restriction of muscular activity and chronic rehydration

The objective of this investigation was to determine the effect of daily intake of fluid and salt supplementation (FSS) on increased urinary losses of microelements that developed during hypokinesia (decreased number of walking steps/d). The studies were performed on 30 endurance-trained male volunteers aged 23–26 yr, with an averaged maximum oxygen uptake of 65 mL/kg/min during 364 d of hypokinesia (HK). All volunteers were divided into three equal groups: Ten volunteers were placed continuously under an average of 10,000 running steps/d (14.2 km/d) (control subjects), ten volunteers subjected continuously to HK without the use of FSS (hypokinetic subjects), and ten volunteers were continuously submitted to HK and consumed daily FSS (hyperhydrated subjects). For the simulation of the hypokinetic effect the hypokinetic and hyperhydrated volunteers were kept under an average of 3,000 walking steps/d (2.7 km/d) for 364 d. Prior to their exposure to HK the volunteers were on an average of 10,000 running steps/d (14.2 km/d). During the prehypokinetic period of 60 d and during the hypokinetic period of 364 d were determined renal excretion of microelements responses of endurance-trained volunteers. In the hyperhydrated volunteers urinary excretion of iron, zinc, copper, manganese, cobalt, nickel, lead, tin, chromium, aluminum, molybdenum, and vanadium decreased, whereas in the hypokinetic volunteers it increased significantly. It was concluded that chronic hyperhydration may be used to attenuate urinary excretion of microelements in endurance-trained volunteers during prolonged restriction of muscular activity.     

Plasma volume changes during and after acute variations of body hydration level in humans

This study examined plasma volume changes (deltaPV) in humans during periods with or without changes in body hydration: exercise-induced dehydration, heat-induced dehydration and glycerol hyperhydration. Repeated measurements of plasma volume were made after two injections of Evans blue. Results were compared to deltaPV calculated from haematocrit (Hct) and blood haemoglobin concentration ([Hb]). Eight well-trained men completed four trials in randomized order: euhydration (control test C), 2.8% dehydration of body mass by passive controlled hyperthermia (D) and by treadmill exercise (60% of their maximal oxygen uptake, VO2max) (E), and hyperhydration (H) by glycerol ingestion. The Hct, [Hb], plasma protein concentrations and plasma osmolality were measured before, during and after the changes in body hydration. Different Hct and [Hb] reference values were obtained to allow for posture-induced variations between and during trials. The deltaPV values calculated after two Evans blue injections were in good agreement with deltaPV calculated from Hct and [Hb]. Compared to the control test, mean plasma volume declined markedly during heat-induced dehydration [-11.4 (SEM 1.7)%] and slightly during exercise-induced dehydration [-4.2 (SEM 0.9)%] (P < 0.001 compared to D), although hyperosmolality was similar in these two trials. Conversely, glycerol hyperhydration induced an increase in plasma volume [+7.5 (SEM 1.0)%]. These results would indicate that, for a given level of dehydration, plasma volume is dramatically decreased during and after heat exposure, while it is better maintained during and after exercise.