Catecholamines, growth hormone, cortisol, insulin, and sex hormones in anaerobic and aerobic exercise

Seventeen male physical education students performed three types of treadmill exercise: (1) progressive exercise to exhaustion, (2) prolonged exercise of 50 min duration at the anaerobic threshold of 4 mmol . l-1 blood lactate (AE), (3) a single bout of short-term high-intensity exercise at 156% of maximal exercise capacity in the progressive test, leading to exhaustion within 1.5 min (ANE). Immediately before and after ANE and before, during, and after AE adrenaline, noradrenaline, growth hormone, cortisol, insulin, testosterone, and oestradiol were determined in venous blood, and glucose and lactate were determined in arterialized blood from the earlobe. Adrenaline and noradrenaline increased 15 fold during ANE and 3--4 fold and 6--9 fold respectively during AE. The adrenaline/noradrenaline ratio was 1 : 3 during ANE and 1 : 10 during AE. Cortisol increased by 35% in ANE (12% of which appeared in the postexercise period) and 54% in AE. Insulin increased during ANE but decreased during AE. Testosterone and oestradiol increased by 14% and 16% during ANE and by 22% and 28% during AE. The results point to a markedly higher emotional stress and higher sympatho-adrenal activity in anaerobic exercise. Growth hormone and cortisol appear to be the more affected by intense prolonged exercise. Taking plasma volume changes and changes of metabolic clearance rates into consideration, neither of the exercise tests appeared to affect secretion of testosterone and oestradiol.     

Hormonal Neuroendocrine and Vasoconstrictor Peptide Responses of Ball Game and Cyclic Sport Elite Athletes by Treadmill Test

ObjectiveOur objective was to evaluate complex hormonal response in ball game and cyclic sport elite athletes through an incremental treadmill test, since, so far, variables in experimental procedures have often hampered comparisons of data.MethodsWe determined anthropometric data, heart rate, maximal oxygen uptake, workload, plasma levels of lactate, adrenaline, noradrenaline, dopamine, cortisol, angiontensinogen and endothelin in control (n = 6), soccer (n = 8), handball (n = 12), kayaking (n = 9) and triathlon (n = 9) groups based on a Bruce protocol through a maximal exercise type of spiroergometric test.ResultsWe obtained significant increases for adrenaline, 2.9- and 3.9-fold by comparing the normalized means for soccer players and kayakers and soccer players and triathletes after/before test, respectively. For noradrenaline, we observed an even stronger, three-time significant difference between each type of ball game and cyclic sport activity.ConclusionsExercise related adrenaline and noradrenaline changes were more pronounced than dopamine plasma level changes and revealed an opportunity to differentiate cyclic and ball game activities and control group upon these parameters. Normalization of concentration ratios of the monitored compounds by the corresponding maximal oxygen uptake reflected better the differences in the response level of adrenaline, noradrenaline, dopamine and cortisol.     

Plasma adrenomedullin response to maximal exercise in healthy subjects.

The aim of the study was to find out whether maximal exercise performed by healthy young men influences plasma adrenomedullin concentration (ADM) and is the peptide level related to the cardiovascular, metabolic and hormonal changes induced by exercise. Ten subjects (age 24+/-1.0 yr) participated in the study. They performed graded bicycle ergometer exercise until exhaustion. Heart rate (HR) and blood pressure (BP) were measured throughout the test. Before and at the end of exercise venous blood samples were taken for [ADM], noradrenaline [NA], adrenaline [A], growth hormone [hGH], cortisol and lactate [LA] determination. Plasma [ADM] decreased during exercise from 1.71+/-0.09 to 1.53+/-0.10 pmol x l(-1) (p<0.01). This was accompanied by increases in plasma catecholamines and [hGH], while plasma cortisol level did not change. Positive correlation was found between the exercise-induced decreases in plasma ADM and diastolic BP. Blood [LA], systolic and mean BP at the end of exercise correlated negatively with plasma [ADM]. No significant interrelationships were found between plasma ADM, catecholamines or the other hormones measured. The present data suggests, that maximal exercise inhibits ADM secretion in young healthy men. Metabolic acidosis and a decrease in peripheral resistance might be involved in this effect.     

Calcitonin gene-related peptide and adrenomedullin release in humans: effects of exercise and hypoxia

Calcitonin gene-related peptide (CGRP) and adrenomedullin (AM) are potent vasorelaxant peptides. This study examined exercise-induced changes in CGRP and AM levels in 12 healthy sea level natives at sea level (SL) and subsequently after 24 h (HA1) and 5 days (HA5) in high altitude hypoxia (4559 m). Plasma values of CGRP, AM, calcitonin, noradrenaline, adrenaline, lactate and heart rate were measured at rest and during maximal exercise (W(max)). On each study day, the dopamine D(2)-receptor antagonist, domperidone (30 mg; n=6), or no medication (n=6) was given 1 h before exercise. W(max) at SL, HA1 and HA5 increased CGRP and AM along with heart rate, lactate and catecholamines, whereas, calcitonin remained unchanged. The maximal CGRP levels at W(max) were significantly decreased at HA1 (74.3+/-6.1 pmol/l; p=0.002) and HA5 (69.6+/-6.0 pmol/l; p<0.001) compared to maximal CGRP at SL (85.1+/-4.9 pmol/l). A similar pattern was observed for lactate and the relation between CGRP and lactate release showed a close linear correlation (r(2)=0.63, P<0.0001). Domperidone produced a marked increase in noradrenaline at W(max), but had no affect on CGRP or AM. In conclusion, CGRP release during hypoxic exercise does not respond to domperidone-induced changes in circulating levels of noradrenaline, rather the release may be directly related to the production of lactate.     

Plasma testosterone and catecholamine responses to physical exercise of different intensities in men

Plasma testosterone, noradrenaline, and adrenaline concentrations during three bicycle ergometer tests of the same total work output (2160 J X kg-1) but different intensity and duration were measured in healthy male subjects. Tests A and B consisted of three consecutive exercise bouts, lasting 6 min each, of either increasing (1.5, 2.0, 2.5 W X kg-1) or constant (2.0, 2.0, 2.0 W X kg-1) work loads, respectively. In test C the subjects performed two exercise bouts each lasting 4.5 min, with work loads of 4.0 W X kg-1. All the exercise bouts were separated by 1-min periods of rest. Exercise B of constant low intensity resulted only in a small increase in plasma noradrenaline concentration. Exercise A of graded intensity caused an increase in both catecholamine levels, whereas, during the most intensive exercise C, significant elevations in plasma noradrenaline, adrenaline and testosterone concentrations occurred. A significant positive correlation was obtained between the mean value of plasma testosterone and that of adrenaline as well as noradrenaline during exercise. It is concluded that both plasma testosterone and catecholamine responses to physical effort depend more on work intensity than on work duration or total work output.     

The responses of the catecholamines and beta-endorphin to brief maximal exercise in man

The responses to brief maximal exercise of 10 male subjects have been studied. During 30 s of exercise on a non-motorized treadmill, the mean power output (mean +/- SD) was 424.8 +/- 41.9 W, peak power 653.3 +/- 103.0 W and the distance covered was 167.3 +/- 9.7 m. In response to the exercise blood lactate concentrations increased from 0.60 +/- 0.26 to 13.46 +/- 1.71 mmol.l-1 (p less than 0.001) and blood glucose concentrations from 4.25 +/- 0.45 to 5.59 +/- 0.67 mmol.l-1 (p less than 0.001). The severe nature of the exercise is indicated by the fall in blood pH from 7.38 +/- 0.02 to 7.16 +/- 0.07 (p less than 0.001) and the estimated decrease in plasma volume of 11.5 +/- 3.4% (p less than 0.001). The plasma catecholamine concentrations increased from 2.2 +/- 0.6 to 13.4 +/- 6.4 nmol.l-1 (p less than 0.001) and 0.2 +/- 0.2 to 1.4 +/- 0.6 nmol.l-1 (p less than 0.001) for noradrenaline (NA) and adrenaline (AD) respectively. The plasma concentration of the opioid beta-endorphin increased in response to the exercise from less than 5.0 to 10.2 +/- 3.9 p mol.l-1. The post-exercise AD concentrations correlated with those for lactate as well as with changes in pH and the decrease in plasma volume. Post-exercise beta-endorphin levels correlated with the peak speed attained during the sprint and the subjects peak power to weight ratio. These results suggest that the increases in plasma adrenaline are related to those factors that reflect the stress of the exercise and the contribution of anaerobic metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lactate and catecholamine responses in male and female sprinters during a Wingate test

A total of six male and six female sprinters at the same national competition level and aged 18–20 years performed a force/velocity test and a 30-s supramaximal exercise test (Wingate test) on 2 different days, separated by a maximal interval of 15 days. The maximal anaerobic power (W _max) was determined from the force/velocity test, and the mean anaerobic power (W) from the Wingate test. Immediately after the Wingate test, a 5-ml venous blood sample was drawn via a heparinized catheter in an antebrachial vein for subsequent catecholamine (adrenaline and noradrenaline) analysis. After 5 min recovery a few microlitres of capillary blood were also taken for an immediate lactate determination. Even expressed per kilogram lean body mass,W _max andW were significantly lower in women. The lactate and adrenaline responses induced by the Wingate test were also less pronounced in this group whereas the noradrenaline levels were not significantly different in men and women. Above all, very different relationships appeared between lactate, adrenaline, noradenaline and W according to sex. Thus, as reported by other authors, the adrenergic response to a supramaximal exercise seemed to be lower in women than in men. Nevertheless a different training status between the two groups, even at same national competition level, could not be excluded and might contribute, at least in part, to the gender differences observed in the present study.     

Early effects of short-term endurance training on hormonal responses to graded exercise.

Twelve male, sedentary volunteers (22.0 +/-) were submitted to three weeks of a bicycle ergometer training, consisting of 45 min exercise (at 70% VO2max), 4 times in the first week and 3 times in the next 2 weeks. They performed four incremental exercise tests with the power output increased by 50 W every 3 min until volitional exhaustion: two before training (C1 and C2), and after one (T1) and three (T3) weeks of training. Before and after each load the plasma noradrenaline (NA), adrenaline (A) and blood lactate (LA) concentrations were determined in venous blood samples as well as plasma growth hormone (HGH) and cortisol concentrations before and at the end of exercise. A decrease in NA concentration was found already after 1 week of training at power output of 100 W (p<0.01) and 200 W (p<0.05). Similar decline was maintained after 3 weeks of training. No significant training-induced differences in plasma A concentration were found, however, the thresholds for both catecholamines were significantly shifted towards higher values after 3 weeks of training. One week of training caused a decrease in the pre-exercise (p<0.01), as well as post-exercise (p<0.05) plasma cortisol and HGH concentrations. It was concluded that endurance training induced a decrease in HGH, cortisol and NA concentration already after one week of training. A decline of pre-exercise plasma HGH and cortisol levels with time of experiment may, in part, indicate familiarization to exercise protocol.     

Catecholamine release and interrenal response of brown trout, Salmo trutta, exposed to aluminium in acidic water

Cannulated brown trout, Salmo trutta , were exposed for 36 h to synthetic water with a low calcium content of pH 5 and similar synthetic water dosed with aluminium to raise the filterable A1 from 5 to 290 μg 1⁻¹ over the 36-h period. There were no significant disturbances of plasma concentrations of glucose, cortisol or catecholamine (adrenaline and noradrenaline) in fish held in water of pH 5. The addition of aluminium to this acidic synthetic water resulted in a generalized endocrine stress response with a four-fold increase in plasma glucose concentration after 18 h and a significant increase in plasma cortisol concentration from 24 h onwards when filterable A1 exceeded 200 μg 1⁻¹. Plasma catecholamine concentration indicated an adrenergic stress response in aluminium-exposed brown trout. A transient doubling in noradrenaline after 6 h in A1 was followed by a larger increase in both plasma adrenaline and noradrenaline concentrations in fish surviving the 36-h exposure to A1.     

Metabolic and hormonal responses to exhaustive supramaximal running with and without beta-adrenergic blockade

The metabolic and hormonal responses to exhaustive short-term supramaximal exercise were studied in 10 male physical education students. The exercise task was a single bout of running on the treadmill at 22 km X h-1 and 7.5% slope. It was performed with single oral doses of 100 mg Bupranolol (non-selective beta-blockade), 100 mg Metoprolol (beta-1-selective blockade), and placebo. Arterialized capillary and venous blood were sampled until 30 min post exercise. Time to exhaustion was 52.0 +/- 2.6, 47.6 +/- 2.0, and 46.0 +/- 1.9 s in the control, Metroprolol, and Bupranolol experiments. At cessation of exercise, adrenaline and noradrenaline were grossly elevated in all three conditions. Lactate and glucose increased markedly, this being accompanied by increasing insulin in the control and Metoprolol, but not the Bupranolol trials. Glycerol increased moderately, while FFA were depressed. Growth hormone showed a delayed increase at 15 and 30 min post exercise. Cortisol was unaffected by exercise. beta-blockade reduced the increases of lactate, glucose, glycerol, insulin, and growth hormone, exaggerated the depression of FFA and had no effect on cortisol. The results demonstrate that the strong sympatho-adrenal response to exercise of this nature is a major determinant of the increase of glucose at cessation of exercise. The hyperglycemia in concert with beta-2-adrenergic stimulation leads to elevation of insulin. Furthermore, lipolysis is controlled by beta-adrenergic stimulation. The delayed increase of growth hormone seems to be triggered by the declining glucose level during recovery.     

Glucose and free fatty acid utilization during prolonged exercise in prepubertal boys in relation to catecholamine responses.

Ten prepubertal boys performed 60-min cycle exercise at about 60% of their maximal oxygen uptake as previously measured. To measure packed cell volume, plasma glucose, free fatty acids (FFA), glycerol and catecholamines, blood samples were drawn at rest using a heparinized catheter and at the 15th, 30th and 60th min of the exercise and after 30 min of recovery. At rest, the blood glucose concentrations were at the lowest values for normal. Exercise induced a small decrease of blood glucose which was combined with an abrupt increase of the noradrenaline concentration during the first 15 min. The FFA and glycerol concentrations increased throughout the exercise linearly with that of adrenaline. Compared to adults, the FFA uptake expressed per minute and per litre of oxygen uptake was greater in children. These results suggested that it is difficult for children to maintain a constant blood glucose concentration and that prolonged exercise provided a real stimulus to hypoglycaemia. An immediate and large increase in noradrenaline concentration during exercise and a greater utilization of FFA was probably used by children to prevent hypoglycaemia.     

Effect of prolonged dynamic exercise on plasma adrenomedullin concentration in healthy young men.

The aim of the study was to find out whether prolonged exercise influences plasma adrenomedullin (ADM) concentration and whether it is related to the hormonal, metabolic and cardiovascular changes. Eighteen healthy subjects (age 25+/-1 yrs) were submitted to cycle exercise for 90 min at 70% of maximal oxygen uptake. Heart rate (HR) and blood pressure (BP) were measured continously. Before, at 30(th) min, and at the end of exercise venous blood samples were taken for [ADM], noradrenaline [NA], adrenaline [A], atrial natriuretic peptide [ANP], plasma renin activity PRA, interleukin-6 [IL-6] and lactate [LA] determination. Significant increases in plasma ADM and IL-6 were found at 90(th) min whereas other hormones were elevated already at 30(th) min of exercise. Positive correlations were ascertained between [ADM] and [NA] (r=0.47), [ANP] (r=0.35) or [IL-6] (r=0.35) and between exercise-induced increases in [ADM] and [NA] (r=0.38). PRA correlated positively with [NA] and [ANP]. Negative correlation was found between plasma [ADM] and diastolic BP. The present data suggest that increase in sympathetic nervous activity and cytokine induction during prolonged exercise may be involved in plasma ADM release and that increase in ADM and ANP secretion may be a compensatory mechanism against further elevation of blood pressure.     

Catecholamine responses to high intensity cycle ergometer exercise: Body mass or body composition?

The purpose of this study was to compare the sympathoadrenergic and metabolic responses following 30 s of maximal high intensity cycle ergometry exercise when cradle resistive forces were derived from total-body mass (TBM) or fat-free mass (FFM). Increases in peak power output (PPO) and pedal velocity were recorded when resistive forces reflected FFM (953 +/- 114 W vs 1020 +/- 134 W; 134 +/- 8 rpm vs 141 +/- 7 rpm ; P < 0.05). No differences were observed between mean power output (MPO), fatigue index (FI%), work done (WD) or heart rate (HR) when the TBM and FFM protocols were compared. There were no differences between the TBM and FFM protocols for adrenaline (A), noradrenaline (NA) or blood lactate concentrations ([La-]B) recorded at rest, immediately post or 24 h post exercise. However, increases in blood concentrations of A and NA (P < 0.05) were recorded for both the TBM and FFM protocol immediately post exercise. Significant correlations (P < 0.05) were recorded between PPOs, immediate post- exercise NA and [La-]B for both the TBM and FFM protocols. [La-]B levels were also significantly elevated (P < 0.01) immediately post exercise for both the TBM and FFM protocols. The results from this study suggest that greater peak power outputs are obtainable with no subsequent differences in neurophysiological or metabolic stress as determined by plasma A, NA and [La-]B concentrations when resistive forces reflect FFM and not TBM during loading procedures. The findings also indicate that immediate post exercise concentrations return to resting levels 24 h post exercise.     

Effect of moderate incremental exercise, performed in fed and fasted state on cardio-respiratory variables and leptin and ghrelin concentrations in young healthy men.

BACKGROUND: Although hormonal responses to exercise performed in fed state are well documented, far less in known about the effect of a single exercise bout, performed after overnight fasting, on cardio-respiratory responses and hormones secretion. It has been reported that recently discovered hormones as leptin and ghrelin may affect cardiovascular responses at rest. However, their effect on the cardiovascular responses to exercise is unknown. AIMS: This study was designed to determine the effect of overnight fasting on cardio- respiratory responses during moderate incremental exercise. We have hypothesised that fasting / exercise induced changes in plasma leptin / ghrelin concentrations may influence cardiovascular response. MATERIAL AND METHODS: Eight healthy non-smoking men (means +/- SE.: age 23.0 +/- 0.5 years; body mass 71.9 +/- 1.5 kg; height 179.1 +/- 0.8 cm; BMI 22.42 +/- 0.49 kg x m(-2) with VO2max of 3.71 +/- 0.10 l x min(-1)) volunteered for this study. The subjects performed twice an incremental exercise test, with the increase of power output by 30 W every 3 minutes. Tests were performed in a random order: once in the feed state--cycling until exhaustion and second, about one week later, after overnight fasting--cycling until reaching 150 W. RESULTS: In the present study we have compared the results obtained during incremental exercise performed only up to 150 W (59 +/- 2 % of VO2max) both in fed and fasted state. Heart rate measured during exercise at each power output, performed in fasted state was by about 10 bt x min(-1) (p = 0.02) lower then in fed subjects. Respiratory quotient and plasma lactate concentration in fasted state were also significantly (p<0.001) lower than in the fed state. Pre-exercise plasma leptin and ghrelin concentrations were not significantly different in fed and fasted state. Exercise induced increase in hGH was not accompanied by a significant changes in the studied gut hormones such as ghrelin, leptin, and insulin, except for plasma gastrin concentration, which was significantly (p = 0.008) lower in fasting subjects at the power output of 150 W. Plasma [IL-6] at rest before exercise performed in fasted state was significantly (p = 0.03) elevated in relation to the fed state. This was accompanied by significantly higher (p = 0.047) plasma noradrenaline concentration. Plasma IL-6 concentration at rest in fed subjects was negatively correlated with plasma ghrelin concentration (r = -0.73, p < 0.05) and positively correlated with plasma insulin concentration (r = 0.78, p < 0.05). Significant negative correlation (r = -0.90; p < 0.05) was found between plasma insulin and ghrelin concentration at rest in fed subjects. CONCLUSIONS: We have concluded that plasma leptin and ghrelin concentrations have no significant effect on the fasting-induced attenuation of heart rate during exercise. We have postulated that this effect is caused by increased plasma norepinephrine concentration, leading to the increase in systemic vascular resistance and baroreceptor mediated vagal stimulation. Moreover we believe, that the fasting-induced significant increase in plasma IL-6 concentration at rest, accompanied by higher plasma norepinephrine concentration and lower RQ, belongs to the physiological responses, maintaining energy homeostasis in the fasting state.     

Primary and secondary stress responses to line capture in the blue mao mao

Primary and secondary stress responses were measured in wild Scorpis violaceus subjected to burst swimming from angling. Fish were blood sampled from 20 s to 30 min after hooking. Consequent rises in plasma adrenaline (14–316 nmol l⁻¹), noradrenaline (25–345 nmol l⁻¹), and cortisol (0.4–197 ng ml⁻¹) correlated with time since capture, and plasma lactate (0.1–12.2 mmol l⁻¹) reflected work done during intense exercise. Haemoglobin concentration and haematocrit also increased with exercise, and erythrocyte swelling occurred. Wild S. violaceus demonstrated a spontaneity and intensity of exercise not seen in fish acclimatized to aquarium conditions. By contrast, the stress responses of fish in captivity, despite careful husbandry, differed qualitatively and quantitatively from those in the wild. Cannulated fish had higher resting plasma cortisol concentrations (61.9±9.5 ng ml⁻¹) than did rapidly caught wild fish (<5 ng ml⁻¹) and these values were not significantly changed with burst swimming. Catecholamine secretion, possibly suppressed by cortisol, was insufficient to cause erythrocyte swelling. Erythrocyte nucleotides do not play a role in exercise, but are elevated in captive fish. It is hypothesized that primary endocrine responses are triggered by higher cortical processing of sensory information which is fundamentally different in the natural environment.     

CATECHOLAMINES AND β2-ADRENOCEPTOR GENE EXPRESSION BEFORE AND AFTER MAXIMAL INCREMENTAL CYCLE TEST IN YOUNG ICE HOCKEY PLAYERS: RELATION TO WORK PERFORMED

The aim of this study was to assess the plasma adrenaline and noradrenaline concentrations as well as whole blood β₂-adrenoceptor gene (ADRB2) expression in young ice hockey players before and immediately after exercise in relation to performed work. Nineteen Youth National Team ice hockey players were subjected to the maximal incremental cycloergometer exercise. The test was done in the pre-competitive phase of training. Among many parameters the plasma adrenaline and noradrenaline concentrations and ADRB2 gene expression in peripheral blood mononuclear cells (PBMC) were determined before and after exercise. The average performed work was 3261.3 ± 558.3 J · kg⁻¹ and maximal oxygen consumption (VO₂max) for all players was 53.85 ± 3.91 mL · kg⁻¹ min⁻¹. The geometric mean of the ADRB2 gene expression was statistically significantly different before and after exercise (P ≤ 0.05), while adrenaline and noradrenaline levels in plasma significantly increased after exercise. In the analysed group of athletes we found that initial level of plasma noradrenaline correlated with the performed work (r = - 0.55, P < 0.014) and normalized ADRB2 expression before the exercise correlated with the work done by them (r = 0.48, P<0.039). However, no statistically significant correlations were found between the plasma adrenaline or noradrenaline concentrations and ADRB2 gene expression in peripheral blood of the players. The performed work in the maximal incremental exercise test of regularly training young ice hockey players depends on the initial levels of noradrenaline in plasma and ADRB2 mRNA in PBMC.     

Studies on the hormonal regulation of fuel metabolism in the human newborn infant undergoing anaesthesia and surgery

Little is known of the endocrine and metabolic milieu in preterm and term neonates exposed to surgical stress. In order to define the effects of anaesthesia and surgery on the hormonal regulation of intermediary metabolism, the levels of plasma insulin, glucagon, adrenaline and noradrenaline were measured in addition to blood glucose, lactate, pyruvate, alanine, acetoacetate, hydroxybutyrate, glycerol and plasma-free fatty acids in 38 neonates (23 term, 15 preterm) undergoing surgery. Blood samples were drawn pre-operatively, at the end of surgery, and at 6, 12 and 24 h post-operatively. Plasma levels of adrenaline and noradrenaline increased significantly in response to surgery. In term neonates, plasma insulin concentrations were unaltered at the end of surgery, but were significantly increased throughout the post-operative period; plasma glucagon levels were unchanged at the end of surgery but had significantly decreased by 24 h after surgery. Insulin levels in preterm neonates remained unchanged during surgery as well as in the post-operative period. All neonates developed a significant peri-operative hyperglycaemia which persisted up to 12 h after surgery. Blood lactate and pyruvate increased during surgery, accompanied by significant increases in plasma free fatty acids, total ketone bodies and glycerol concentrations by the end of surgery. Blood glucose concentrations were significantly correlated with plasma adrenaline levels at the end of surgery and with plasma glucagon at 6 h post-operatively. The insulin/glucose ratio was significantly decreased at the end of surgery in term and preterm neonates. Further analysis showed that total parenteral nutrition given just before surgery and thiopentone anaesthesia given during surgery significantly augmented the peri-operative hyperglycaemic response of term neonates. Thus, stress-related hormonal changes in preterm and term neonates may precipitate a catabolic state characterized by glycogenolysis, gluconeogenesis, lipolysis and mobilization of gluconeogenic substrates in the post-operative period. Prevention of these metabolic derangements by anaesthetic or hormonal manipulation may possibly help to improve the clinical outcome of neonates undergoing surgery.     

Sex-related differences in free plasma catecholamines in individuals of similar performance ability during graded ergometric exercise

Sex-related differences of catecholamine responses were evaluated in nine healthy women and six age-matched men at rest and during incremental treadmill exercise. Heart rate, oxygen uptake (VO2), glucose and lactate blood levels as well as the free plasma catecholamines, noradrenaline and adrenaline, were determined. No significant differences were observed for these parameters between the two groups at rest. The females had relative VO2max and maximal running velocities similar to the males, which points to a comparable dynamic performance ability. However, at identical work loads, noradrenaline, adrenaline and glucose levels were significantly higher in women than in men. Lactate, heart rate and relative VO2 showed a similar tendency at submaximal exercise levels, indicating higher strain at identical stress levels in women. The reason for the higher sympathetic activity in women at identical work loads may be their relatively smaller skeletal muscle mass in relation to the loads during this test.     

Substrate mobilization and hormonal changes in rainbow trout (Oncorhynchus mykiss,L.) and common carp (Cyprinus carpio,L.) during deep hypoxia and subsequent recovery

Common carp (at 20°C) and rainbow trout (at 15°C) were fitted with an indwelling cannula in the dorsal aorta. The fish were exposed to a controlled decline of waterpO₂ followed by 90 min deep hypoxia at 0.3 kPa (carp) or 4.8 kPa (trout). Thereafter, normoxic recovery was monitored in both species for 48 h. At regular intervals blood samples were analysed for glucose, lactate, free fatty acids, adrenaline, noradrenaline and cortisol. The oxygen restriction was maximal in both species and resulted in a significant increase of plasma lactate levels. In carp, adrenaline, noradrenaline and cortisol levels increased to 2, 50, and 753 ng·ml^-1 respectively during anoxia, whereas in trout these hormones increased to 12, 8 and 735 ng·ml^-1 respectively during hypoxia. In hypoxic trout, the plasma levels of glucose (3 mol·l^-1) were increased modestly whereas levels of free fatty acids (0.25 mmol·l^-1) were decreased to 0.15 mmol·l^-1. In carp, however, a marked and prolonged hyperglycaemia (from 5 to 10 mmol·l^-1) and a significant continuous depression of plasma levels of free fatty acids (from 0.4 to 0.2 mmol·l^-1) were observed indicating a difference in metabolic organization. It is suggested that hyperglycaemia is likely to be the result of hepatic glycogenolysis, stimulated by circulating catecholamines and a stimulation of gluconeogenesis by cortisol during recovery. The mechanism for the decline of plasma levels of free fatty acids is most probably a reduction of lipolytic activity, which appears to be an adaptation to hypoxia.     

Leucocytosis, thrombocytosis, and plasma osmolality during rest and exercise: an hypothesis.

The mechanism for inducing leucocytosis (increase in white blood cells) and thrombocytosis (increase in platelets) during exercise is unclear. Because plasma osmolality (Osm) may influence T-cell proliferation, Osm and the number of leucocytes (WBC) and platelets in blood were measured periodically during a 90 min rest period, and were compared with those during upright sitting ergometer exercise in six untrained, healthy men who cycled for 70 min at 71% of their maximal oxygen uptake (VO2max). There were 6 experiments in which the subjects drank different fluid formulations (10 ml x kg(-1) of various ionic and osmotic concentrations intermittently during 60 min of the rest period and during the exercise period. Osmolality, and WBC and platelet counts increased significantly (p < 0.05) within the first 10 min of exercise, but the additional 60 min of exercise did not significantly change the leucocytosis or thrombocytosis. There were low but significant correlations between individual values of total WBC and total Osm during exercise (r0.001(2),284 = 0.39) and during rest plus exercise (r0.001(2),499 = 0.43). With combined data from the six experiments, mean Osm correlated highly and significantly with both mean WBC (r0.001(2),6 = 0.95, p < 0.001) and mean platelets (r0.001(2),6 = 0.94, p < 0.01) during the exercise phase. These data indicate that increases in leucocytes, thrombocytes, and osmolality occur primarily within the first 10 min of high-intensity exercise, but neither hypovolemia nor hyperthermia during exercise contributed to the leucocytosis, thrombocytosis, or hyperosmolality. The high correlations between plasma Osm and WBC or platelet counts suggest changes in osmolality may contribute to the mechanism of leucocytosis and thrombocytosis induced by exercise.