Urinary and serum electrolyte changes in athletes during periodic and continuous hypokinetic and ambulatory conditions

Hypokinesia (HK) (diminished movement) induces significant electrolyte changes, but little is known about the effect of periodic hypokinesia (PHK) on minerals. The aim of this study was to measure the effect of PHK and continuous hypokinesia (CHK) on urinary and serum electrolytes. Studies were done during a 30-d period of prehypokinesia (HK) and during 364 d of PHK and CHK periods. Thirty male athletes aged 24.6±7.7 yr were chosen as subjects. They were equally divided into three groups: unrestricted ambulatory control subjects (UACS), continuously hypokinetic subjects (CHKS), and periodically hypokinetic subjects (PHKS). The UACS group experienced no changes in the daily activities and regular training and they were maintained under an average running distance of 11.7 km/d. The CHKS group was limited to an average walking distance of 0.7 km/d; and the PHKS group was limited to an average walking distance of 0.7 and running distance of 11.7 km/d for 5 d and 2 d/wk, respectively, for a period of 364 d. Urinary and serum phosphate (P), calcium (Ca), sodium (Na) and potassium (K), serum intact parathyroid hormone (iPTH), calcitonin (CT), plasma renin activity (PRA) and aldosterone (PA) levels, food and water intakes, and physical characteristics were measured. Urinary P, Ca, Na, and K loss, serum Ca, P, Na, and K, and PRA and PA values increased significantly (p≤0.01), whereas serum iPTH and CT levels decreased significantly (p≤0.01) in the PHKS and CHKS groups when compared with the UACS group. However, significant (p≤0.01) differences were observed between PHKS and CHKS groups regarding urinary and serum electrolytes, serum and plasma hormones. Food and water intakes, body weight, body fat, and peak oxygen uptake decreased significantly (p ≤ 0.01) in the CHKS group when compared with PHKS and UACS groups. Food and fluid intakes, body fat, and body weight increased significantly (p≤0.01), whereas peak oxygen uptake remained significantly (p≤0.01) higher in the PHKS group when compared with the CHKS group. Serum and urinary minerals, serum hormones, food and fluid intakes, and physical characteristics did not change significantly (p>0.01) in the UACS group when compared with their baseline control values. It was shown that both PHK and CHK induce significant serum and urinary electrolyte changes. However, urinary and serum electrolyte changes were significantly (p≤0.01) greater during PHK than CHK. It was concluded that the greater the stability of muscular activity, the smaller the serum and urinary electrolyte changes during prolonged HK.     

Electrolyte changes in plasma and urine of athletes during acute and rigorous bed rest and ambulatory conditions

Rigorous bed rest (RBR) induces significant electrolyte changes, but little it is not known about the effect of acute bed rest (ABR) (i.e., abrupt confinement to a RBR). The aim of this study was to measure urinary and plasma electrolyte changes during ABR and RBR conditions. The studies were done during 3 d of a pre-bed-rest (BR) period and during 7 d of an ABR and RBR period. Thirty male trained athletes aged, 24.4 ± 6.6 yr were chosen as subjects. They were divided equally into three groups: unrestricted ambulatory control subjects (UACS), acute-bed-rested subjects (ABRS), and rigorous-bed-rested subjects (RBRS). The UACS group experienced no changes in professional training and daily activities. The ABRS were submitted abruptly to a RBR regimen and without having any prior knowledge of the exact date and time when they would be subjected to an RBR regimen. The RBRS were subjected to an RBR regime on a predetermined date and time known to them from the beginning of the study. Sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), and phosphate (P) in plasma and urine, plasma renin activity (PRA) and plasma aldosterone (PA), physical characteristics, peak oxygen uptake, and food and water intakes were measured. Urinary Na, K, Ca, Mg, and P excretion and plasma Na, K, Mg, Ca, and P concentration, PRA, and PA concentration increased significantly (p ≤ 0.01), whereas body weight, peak oxygen uptake, and food and water intakes decreased significantly in the ABRS and RBRS groups when compared with the UACS group. However, urinary and plasma Na, K, Mg, P, and Ca, PRA, and PA values increased much faster and were much greater in the ABRS group than in the RBRS group. Plasma and urinary Na, K, Ca, Mg, and P, PRA and PA levels, food and water intakes, body weight, and peak oxygen uptake did not change significantly in the UACS group when compared with its baseline control values. It was shown that RBR and ABR conditions induce significant increases in urinary and plasma electrolytes; however, urinary and plasma electrolyte changes appeared much faster and were much greater in the ABRS group than the RBRS group. It was concluded that the more abruptly motor activity is ended, the faster and the greater the urinary and plasma electrolyte change.     

Potassium supplements’ effect on potassium balance in athletes during prolonged hypokinetic and ambulatory conditions

Electrolyte supplements may be used to prevent changes in electrolyte balance during hypokinesia (diminished movement). The aim of this study was to measure the effect of potassium (K) supplements on K balance 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 25.1±4.4 yr were chosen as subjects. They were divided equally into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS) and supplemented ambulatory control subjects (SACS). The SHKS and UHKS groups were kept under an average walking distance of 0.7 km/d. The SACS and SHKS groups were supplemented daily with 50.0 mg elemental potassium chloride (KCl) per kilogram body weight. The K balance, fecal K excretion, urinary K, sodium (Na), and chloride (Cl) excretion, plasma K, Na, and Cl concentration, plasma renin activity (PRA) and plasma aldosterone (PA) concentration, anthropometric characteristics and peak oxygen uptake were measured. Negative K balance, fecal K excretion, urinary K, Na, and Cl excretion, plasma K, Na, and Cl concentration, and PRA and PA concentration increased significantly (p≤0.01), whereas body weight and peak oxygen uptake decreased significantly in the SHKS and UHKS groups when compared with SACS and UACS groups. However, the measured parameters changed much faster and much more in SHKS group than UHKS group. By contrast, K balance, fecal, urinary, and plasma K, plasma hormones, body weight, and peak oxygen uptake did not change significantly in the SACS and UACS groups when compared with the baseline control values. It was concluded that prolonged HK induces a significant negative K balance associated with increased plasma K concentration and urinary and fecal K excretion. However, negative K balance appeared much faster and was much greater in the SHKS group than UHKS group. Thus, K supplementation was not effective in preventing negative K balance during prolonged HK.     

Calcium measurements in primates during and after hypokinesia in establishing calcium deficiency during prolonged hypokinesia

Hypokinesia (diminished movement) induces significant calcium (Ca) changes, but little is known about the effect of hypokinesia (HK) on Ca deficiency. Measuring Ca changes during and after HK the aim of this study was to determine Ca deficiency during prolonged HK. Studies were done on 12 male Macaca mulatta (rhesus monkeys) aged 3–5 yr (5.58–6.42 kg) during a 90-d pre-HK period, a 90-d HK period, and a 15-d post-HK period. Monkeys were equally divided into two groups: vivarium control monkeys (VCM) and hypokinetic monkeys (HKM). Hypokinetic monkeys were kept in small individual cages that restricted their movements in all directions without hindering food and water intakes. Urinary, fecal, and serum Ca, urinary and serum magnesium (Mg) and phosphate (P), serum intact parathyroid hormone (iPTH), and calcitonin (CT) concentration, body weight, food intake, fluid consumed and eliminated in urine were measured. During the HK period, fecal Ca loss, urinary Ca, P, and Mg excretion, fluid elimination, and serum P, Ca, and Mg concentration increased significantly (p≤0.01), whereas serum iPTH and CT concentration, food and fluid intakes, and body weight decreased significantly (p≤0.01) in the HKM group when compared with the VCM group. During the initial days of the post-HK period, serum Ca, Mg, and P concentration, fecal Ca loss, urinary Ca, Mg, and P excretion, and fluid elimination decreased significantly (p≤0.01), whereas fluid intake increased significantly (p≤0.01) in the HKM group when compared with the VCM group. Food intake, body weight, and serum iPTH and CT concentrations remained significantly (p≤0.01) depressed in the HKP group when compared with the VCM; however, they increased as the duration of the post-HK period increased. By contrast, the corresponding parameters remained stable in the VCM group when compared with the baseline control values. It was shown that fecal and urinary Ca loss and serum Ca concentration increases significantly during HK, whereas during post-HK fecal, urinary, and serum Ca decreases significantly. It was concluded that significant decrease of serum, urinary, and fecal Ca during post-HK may suggest the presence of Ca deficiency during prolonged HK.     

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.     

Calcium supplementation effect on calcium balance in endurance-trained athletes during prolonged hypokinesia and ambulatory conditions

Calcium (Ca) supplements may be used to normalize Ca-balance changes but little is known about the effect of Ca supplements on Ca balance during hypokinesia (decreased kilometers per day). The aim of this study was to evaluate the effect of daily intakes of Ca supplements on Ca balance during hypokinesia (HK). Studies were done during 30 d of a pre-HK period and during 364 d of a HK period. Forty male athletes aged 23–26 yr were chosen as subjects. They were divided equally into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS), and supplemented ambulatory control subjects (SACS). The SHKS and UHKS groups were kept under an average running distance of 0.7 km/d. In the SHKS and SACS groups supplemented with 35.0 mg Ca lactate/kg body weight. Fecal Ca loss, urinary excretion of Ca and phosphate (P), serum concentrations of ionized calcium (Ca_I) total Ca, P, and Ca balance, intact parathyroid hormone (iPTH) and 1,25 dihydroxyvitamin D (1,25(OH)2D), anthropometric characteristics and peak oxygen uptake were measured. Fecal Ca excretion, urinary Ca and P excretion, serum Ca_I, total Ca, and P concentration, and negative Ca balanced increased significantly (p ≤ 0.01) in the SHKS and UHKS groups when compared with the SACS and UACS groups. Serum, urinary, and fecal Ca changes were much greater and appeared much faster in the SHKS group than in the UHKS group. Serum iPTH and 1,25 (OH)2 D, body weight, and peak oxygen uptake decreased significantly (p ≤ 0.01) in the SHKS and UHKS groups when compared with the SACS and UACS groups. In contrast, the corresponding parameters remained stable in the SACS and UACS groups when compared with the baseline control values. It was concluded that during prolonged HK, urinary and fecal Ca excretion and serum Ca concentration increased significantly despite the presence of a negative Ca balance; thus, Ca supplements cannot be used to normalize negative Ca balance during prolonged HK.     

Potassium changes in trained subjects after potassium loading and during restriction of muscular activity and chronic hyperhydration

The objective of this investigation was to determine whether urinary and plasma potassium changes developed during prolonged hypokinesia (HK) (decreased number of km/d) in endurance-trained subjects could be minimized or reversed with a daily intake of fluid and salt supplementation (FSS). The studies were performed on 30 endurance-trained male volunteers aged 23–26 yr with an average peak oxygen uptake of 65 mL/kg min during 364 d of HK. All volunteers were on an average of 13.8 km/d prior to their exposure to HK. All volunteers were randomly divided into three groups: 10 volunteers were placed continuously under an average of 14.0 km/d (control subjects), 10 volunteers were subjected continuously to an average of 2.7 km/d (unsupplemented hypokinetic subjects), and 10 volunteers were submitted continuously to an average of 2.7 km/d, and consumed daily an additional amount of 0.1 g sodium chloride (NaCl)/kg body wt and 30 mL water/kg body wt (supplemented hypokinetic subjects). During the prehypokinetic period of 60 d and during the hypokinetic period of 364 d, potassium loading tests were performed with 1.5–1.7 mEq potassium chloride/kg body wt, and potassium, sodium, and chloride excretion in urine and potassium, sodium, and chloride in plasma were determined. In the unsupplemented hypokinetic volunteers, urinary excretion of electrolytes and concentrations of electrolytes in plasma increased significantly as compared to the control and supplemented hypokinetic groups of volunteers. It was concluded that daily intake of fluid and salt supplementation had a favorable effect on regulation of urinary and plasma potassium changes in trained subjects during prolonged HK.     

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.     

Analysis of imidazoles and triazoles in biological samples after MicroExtraction by packed sorbent

This paper reports the MEPS-HPLC-DAD method for the simultaneous determination of 12 azole drugs (bifonazole, butoconazole, clotrimazole, econazole, itraconazole, ketoconazole, miconazole, posaconazole, ravuconazole, terconazole, tioconazole and voriconazole) administered to treat different systemic and topical fungal infections, in biological samples. Azole drugs separation was performed in 36?min. The analytical method was validated in the ranges as follows: 0.02–5?μg mL^?1 for ravuconazole; 0.2–5?μg mL^?1 for terconazole; 0.05–5?μg mL^?1 for the other compounds. Human plasma and urine were used as biological samples during the analysis, while benzyl-4-hydroxybenzoate was used as an internal standard. The precision (RSD%) and trueness (Bias%) values fulfill with International Guidelines requirements. To the best of our knowledge, this is the first HPLC-DAD procedure coupled to MEPS, which provides the simultaneous analysis of 12 azole drugs, available in the market, in human plasma and urine. Moreover, the method was successfully applied for the quantitative determination of two model drugs (itraconazole and miconazole) after oral administration in real samples.     

Muscle electrolyte measurements during and after hypokinesia in determining muscle electrolyte depletion during hypokinesia in the rat

Hypokinesia (diminished movement) induces muscle mineral depletion. However, the mechanism of muscle mineral depletion during hypokinesia (HK) remains unknown. Measuring electrolyte retention and electrolyte values in muscle, plasma, and urine during and after HK, the aim of this study was to discover if HK could depress mineral retention and lead to muscle mineral depletion. Studies were done on 204 13-wk-old male Wistar rats (370–390 g) during 10 d pre-HK period, 98 d HK period, and 15 d post-HK period. Rats were equally divided into two groups: vivarium control rats (VCR) and hypokinetic rats (HKR). All hypokinetic rats were kept for 98 d in small individual cages, which restricted their movements in all directions without hindering food and water intakes. All control rats were housed for 98 d in individual cages under vivarium control conditions. Both groups of rats were pair-fed. During the HK period skeletal muscle sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), and water content and electrolyte retention decreased significantly (p < 0.05), while urinary and plasma electrolyte levels increased significantly (p < 0.05) in HKR compared with their pre-HK values and their respective VCR. During the initial days of the post-HK period, mineral retention increased significantly (p < 0.05), plasma and urinary electrolyte level decreased significantly (p < 0.05), while muscle electrolyte and water content remained significantly (p < 0.05) depressed in HKR compared with VCR. Muscle mineral and water content, electrolyte retention, plasma, and urinary electrolyte values did not change in VCR compared with their pre-HK values. It was concluded that during HK decreased muscle mineral content may suggest muscle mineral depletion, while increased urinary electrolyte loss and muscle mineral depletion may demonstrate reduced mineral retention. Reduced electrolyte excretion and depressed muscle mineral content during post-HK may indicate skeletal muscle mineral depletion during HK. Dissociation between electrolyte retention and muscle mineral depletion may demonstrate the presence of decreased electrolyte retention as the mechanism of muscle electrolyte depletion during prolonged HK.     

三江平原草甸白浆土种稻后土壤理化性质变化

土壤质量变化与更新是农业发展和土壤管理的判断准则.白浆土是三江平原主要水田土壤,但旱田改水田后缺乏对其土壤质量变化规律的研究.本研究以不同种稻年限白浆土为调查对象,探讨其土壤理化性质演变特征.结果表明: 白浆土种稻后,耕层(厚16~23 cm)和犁底层(厚6~8 cm)土壤有机碳、还原物质总量增加,耕层深度随种稻年限增加呈逐渐增加趋势,犁底层无明显变化,心土层(厚20 cm)与旱田无显著差异;土壤中Fe²⁺和Mn²⁺有向下迁移现象,但只迁移到犁底层;耕层和犁底层土壤固相比率比种稻前增加,犁底层固相比率由47.8%增加到70.0%,容重由1.22 g·cm^-3增加到1.77 g·cm^-3,土壤孔隙总量降低,微孔隙比例增加,白浆土种稻后有黏粒淋溶淀积现象.白浆土种稻后,土壤物理和化学性质的变化特征与水稻土的演变规律既有一致性,又有其特殊性.     

Platelet selenium in children with normal and low selenium intake

The concentration of selenium was determined by instrumental neutron activation analysis in erythrocytes, platelets, and plasma of eight dietetically treated children with phenylketonuria (n=6) or maple-syrup-urine disease (n=2) with low selenium intake and for ten children with normal selenium intake. The normal selenium concentration in platelets was about 600 ng/g and about five times higher than in erythrocytes of the same children. A decreased selenium concentration in platelets was seen only when the corresponding concentrations in erythrocytes and plasma were very low. This suggests a special role of selenium in platelets.