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Biomedical subjects

K Nazar

Publications and source records attributed to K Nazar.

120 records · Page 7Linked to original sources
PubMedDate not supplied

Thermoregulatory and metabolic responses to repeated bouts of prolonged cycle-ergometer exercise in man.

Changes in body temperature, oxygen uptake (VO2), heart rate (HR), sweating rate and plasma osmolarity were examined in 10 human subjects, performing four successive 30 min exercise-bouts of the same intensity (50% VO2 max) separated by 30 min rest periods. In spite of the rest intervals and replacement of body fluid loss there was a progressive increase in VO2. HR, rectal (Tre) and mean body (Tb) temperatures in consecutive exercise bouts. The thermoregulatory efficiency showed an increasing tendency, and a delay in the sweating response at the beginning of each exercise was shortened. It is concluded that a drift in metabolic and temperature responses to exercise, reported throughout a long-term continuous work, occurs also in the euhydrated subjects performing a prolonged intermittent exercise. It is not caused by an impaired thermoregulation during exercise but rather by insufficient restitution of metabolic processes during rest intervals.

Adult↗
PubMedDate not supplied

Plasma insulin and C-peptide responses to oral glucose load after physical exercise in men with normal and impaired glucose tolerance.

Blood glucose, plasma insulin and C-peptide responses to oral glucose tolerance test (OGTT) were studied under basal conditions and immediately after 90-min exercise (60% VO2 max) in nondiabetic subjects with normal or impaired glucose tolerance. During the postexercise recovery blood glucose response to OGTT was increased in normal subjects and markedly decreased in those with impaired glucose tolerance, while insulin and C-peptide responses were diminished in both subgroups. The ratio of blood glucose to insulin was similarly elevated in all subjects. Comparing with basal conditions no significant changes were found in C-peptide to insulin ratio in response to OGTT after exercise, although a tendency towards an elevation of this ratio was noted in the subjects with impaired glucose tolerance. The data indicate that the reduced insulin response to OGTT during postexercise recovery in healthy subjects is due to diminished insulin secretion without any substantial changes in the hormone removal from blood, whereas in the glucose intolerant men the latter process may be enhanced.

Adult↗
PubMedDate not supplied

Prolonged hyperadrenalinemia impairs exercise ability in rats.

This study was performed on rats with sustained (24 h) hyperadrenalinemia produced by sc implantation of retard adrenaline (A) tablets. Comparing with control, sham-operated animals, in A-treated rats duration of endurance exercise until exhaustion was shortened by approx. 40%. This was accompanied by: significant decreases of the pre-exercise muscle glycogen and creatine phosphate values in both "slow twitching" (soleus) and "fast twitching" (white portion of gastrocnemius) muscles, and of ATP content in soleus. Muscle lactate and pyruvate contents as well as blood glucose and FFA levels were elevated. After exercise muscle substrate and metabolite contents were similar in both groups in spite of the difference in exercise duration. It is concluded that prolonged hyperadrenalinemia diminishes the intramuscular energy substrate content, thereby reducing endurance capacity of rats.

Animals↗
PubMedDate not supplied

Progressive enhancement of body temperature responses to consecutive exercise-bouts of the same intensity in dogs.

Progressive enhancement of body temperature responses to consecutive exercise-bouts of the same intensity in dogs. Acta physiol. pol., 1985, 36 (3): 165-174. Changes in rectal (Tre), muscle (Tm), and hypothalamic (Thy) temperatures, plasma osmolality, and some intermediary metabolic variables were examined in dogs performing four successive exercise-bouts of the same intensity. During the rest-intervals separating the exercise-bouts body temperatures returned to initial levels and water losses were replaced. Tm and Tre responses to consecutive exercise-bouts were progressively increasing. Similar tendency was found in Thy changes. Cardiac and respiratory frequencies attained the same levels in all four exercise-bouts, while blood lactate and FFA concentrations were increasing and blood glucose level was decreasing progressively. No changes in plasma osmolality was noted. Exercise-induced increases in Tm correlated positively with plasma FFA concentration (r = 0.68). Body temperature responses to exercise were reduced by beta-adrenergic blockade. It is concluded that the enhancement of the thermal responses to consecutive exercise-bouts can be related to the metabolic action of catecholamines.

Animals↗
PubMedDate not supplied

Diminished adrenergic response to 2-deoxy-D-glucose after prolonged, exhausting physical exercise in dogs.

Effect of 2-deoxy-D-glucose (2DG) on plasma adrenaline, glucose and free fatty acid concentrations was studied in dogs under control conditions and after prolonged, exhausting physical exercise. The increase in all three variables in response to 2DG was significantly reduced following the exercise. The results suggest diminished responsiveness of adrenal medulla to the glucopenic stimulus after exhausting exercise.

Animals↗
PubMedDate not supplied

Effect of prolonged exhausting exercise on the adrenal cortex response to ACTH.

Plasma cortison response of ACTH injection was studied in dogs under control conditions and after a prolonged exercise performed until exhaustion. Exercise induced a marked increase in plasma cortisol concentration but no significant differences were found in the level of plasma cortisol following ACTH injection between the control and post-exercise animals.

Adrenal Cortex↗
PubMedDate not supplied

Plasma and urinary catecholamines and metabolites during physical exercise in essential hypertension.

The effect of physical exercise on plasma catecholamines and urinary catecholamines and metabolites was studied in 11 patients with established essential hypertension, 5 patients with borderline hypertension, and 9 healthy volunteers. Resting plasma noradrenaline and the changes following exercise were similar in all the investigated groups. Although the resting urinary noradrenaline excretion was similar in patients and in controls, an exaggerated increase of noradrenaline excretion occurred in hypertensive patients during physical work. This finding suggests sympathetic overreactivity in essential hypertension. The increased plasma levels of adrenaline, found in established hypertension, were associated with its diminished urinary clearance. These results imply altered renal handling of adrenaline in essential hypertension. Physical exercise was associated with enhancement of metabolism of noradrenaline to 3-methoxy,4-hydroxy-phenylglycol in all groups of subjects, but the stimulation of this pathway was particularly pronounced in healthy subjects. In essential hypertension, the pattern of urinary excretion of catecholamines and metabolites suggests impaired noradrenaline metabolism during exercise. The only characteristic feature of borderline, as opposed to established hypertension, was the increased urinary excretion of dopamine.

Adult↗
PubMedDate not supplied

Plasma renin activity, aldosterone and cortisol levels during physical exercise in essential hypertension.

Plasma renin activity, aldosterone and cortisol levels, as well as renal blood flow were studied in borderline and established hypertensive patients and in healthy control subjects at rest and following graded dynamic upright exercise. Resting plasma renin activity was elevated in established hypertension, renal blood flow at rest was decreased in patients with borderline hypertension but its per cent decrease during exercise was similar in all groups. Following exercise, plasma renin activity increased in all groups but a step-wise increase with graded exercise occurred only in borderline hypertension. Resting plasma aldosterone and cortisol levels were similar in all groups. In the hypertension patients physical exercise was associated with disproportional changes of plasma renin activity and aldosterone levels. Plasma cortisol displayed patterns which were roughly similar to those or aldosterone in the control group an in established hypertension, but not in the borderline group, where the most pronounced increased of aldosterone level was associated with the lowest level of cortisol. It is concluded that the physiological response of the renin-angiotensin-aldosterone system to physical exercise is altered in essential hypertension.

Adult↗