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Biomedical subjects

K Nazar

Publications and source records attributed to K Nazar.

At least 91 records · Page 5Linked to original sources
PubMed1982

Changes in muscle lipoprotein lipase activity during exercise in dogs fed on a mixed fat-rich meal.

Skeletal muscle lipoprotein lipase activity LPLA was compared in dogs performing prolonged treadmill exercise after 20-22 h fasting or 4 h following mixed fat-rich meal ingestion. In the fasting state muscle LPLA increased progressively during 2 h exercise. In fed dogs the resting value of the muscle LPLA was considerably lower than that in the fasting state, and no increase in the enzyme activity occurred during physical effort. The inhibition of the muscle LPLA by the meal ingestion can be attributed to the persisting effects of increased plasma insulin and/or FFA concentrations, found at the beginning of exercise.

Animals↗
PubMed1982

Chylomicron triglyceride metabolism in resting and exercising fed dogs.

The turnover of circulating triglycerides (TG) was determined in dogs during rest, following ingestion of food that included corn oil, and in the final period of a 1-h treadmill exercise of moderate intensity (72-84 m/min). In all cases the loss of [14C]TG from the plasma followed a first-order process. The fractional removal rate constant at rest was 26.5 +/- 1.9% (SE) n = 10) of the circulating pool size per minute, and it was increased slightly to 33.8 +/- 3.6% (n = 7) per minute during exercise. The uptake of plasma TG-derived fatty acids (5 min postinjection) was increased (P less than 0.05) in working muscle, whereas the TG uptake in fat tended to decrease. Further, the percent of TG-derived fatty acids found in the muscle's acylglyceride pool was less (90.0 +/- 3.6 vs. 53.5 +/- 1.8%), while that in the muscle's free fatty acid pool was greater (12.3 +/- 36.1 +/- 4.7%) in working compared with resting muscle. Thus the fourfold greater quantity of plasma TG-derived fatty acids found in the working muscle's free fatty acid pool could account for the entire increased TG uptake caused by exercise. This suggests that, in the fed state, circulating TG could represent a potential source of fatty acids for beta-oxidation in working muscle. However, the importance of plasma TG-derived fatty acids as an energy substrate during muscle use in a postprandial state has yet to be determined quantitatively.

Adipose Tissue↗
PubMed1980

Extracellular hyperosmolality and body temperature during physical exercise in dogs.

The purpose of this study was to test the hypothesis that thermoregulation during exercise can be affected by extracellular fluid hyperosmolality [Osm] without changing the plasma Na+ concentration. The effects of preexercise venous infusions of hypertonic mannitol and NaCl solutions on rectal temperature (Tre) responses were compared in dogs running at moderate intensity for 60 min on a treadmill. Plasma E1Na+] was increased by 12 meq/l (P less than 0.05) after NaCl infusion, and decreased by 9 meq/l (P less than 0.05) after mannitol infusion. Both infusions increased plasma [Osm] by 15 mosmol/kg (P less than 0.05). After both infusions, Tre was essentially constant during 60 min rest. However, compared with the noninfusion exercise increase in Tre of 1.3 degrees C, Tre increased by 1.9 degrees C (delta delta Tre = 0.5 degrees C, P less than 0.05) after both postinfusion exercise experiments. It was concluded that inducing extracellular hyperosmolality, without elevating plasma [Na+], can induce excessive increases in Tre during exercise but not at rest.

Animals↗
PubMed1980

Physiological responses to prolonged physical exercise in dogs.

1. Duration of exercise until exhaustion is significantly correlated with body weight of dogs. 2. Rectal temperature (Tre) achieved at the end of the effort depends on the resting value of Tre, but the exercise-induced increases in Tre are unrelated to the initial Tre. 3. The magnitude of exercise-induced decrease in blood glucose (BG) level is positively correlated with the resting BG level and negatively correlated with the elevations of the plasma free fatty-acid (FFA) concentration. 4. A significant positive relationship is found between the exercise-induced increases in the plasma FFA levels and noradrenalinaemia.

17-Hydroxycorticosteroids↗
PubMed1979

Plasma noradrenaline response to sustained handgrip in patients with essential hypertension.

The responses of plasma noradrenaline, arterial blood pressure, and heart rate to sustained handgrip at 30% maximal voluntary contraction were studied in untreated patients with essential hypertension and in healthy subjects of comparable age. There were no significant differences between these two groups in the intensity and duration of handgrip. Increases in heart rate and blood pressure induced by the effort were similar in hypertensive patients and normotensive control subjects, whereas the absolute levels of blood pressure were considerably higher in the patients. In the first 1-2 min of exercise the increases in plasma noradrenaline concentration were similar in both groups. Subsequently, plasma noradrenaline concentration tended to plateau in hypertensive patients while in control subjects it continued to increase. The elevation of plasma noradrenaline in the last minute of effort was, therefore, significantly smaller in hypertensive patients than in the control group.

Adolescent↗
PubMed1979

Lipoprotein lipase activity in the skeletal muscle during physical exercise in dogs.

Changes in lipoprotein lipase activity /LPLA/ in the quadriceps femoris muscle were followed in ten dogs during 3-hour treadmill exercise and 2-hour post-exercise recovery period. During the first hour of exercise muscle LPLA steeply increased. Subsequently the enzyme activity tended to plateau. After exercise LPLA decreased to the pre-exercise value within 1 hour. It is concluded that exercise increases the ability of skeletal muscles to remove triglycerides from the circulation.

Animals↗
PubMed1976

The nature of the training response; peripheral and central adaptations of one-legged exercise.

13 male subjects were studied and placed in 3 groups. Each group exercised one leg with sprint (S), or endurance (E) training and the other leg oppositely or not at all (NT). Oxygen uptake (Vo2), heart rate and blood lactate were measured for each leg separately and for both legs together during submaximal and maximal bicycle work before and after 4 weeks of training with 4-5 sessions per week. Muscle samples were obtained from the quadriceps muscle and assayed for succinate dehydrogenase (SDH) activity, and stained for myofibrillar ATPase. In addition, eight of the subjects performed after the training two-legged exercise at 70% Vo2 max for one hour. The measurements included muscle glycogen and lactate concentrations of the two legs as well as the blood flow and the a-v difference for O2, glucose and lactate.

Adaptation, Physiological↗
PubMed1976

Ion-osmotic hyperthermia during exercise in dogs.

The influence of intravenous infusions of various concentrations of NaCl solutions on temperature regulation was investigated in dogs at rest and during moderate exercise for 1 h on a treadmill. Infusion of hypertonic solutions either before and during exercise resulted in elevated (P less than 0.05) plasma Na+ and osmotic concentrations and produced higher equilibrium levels (P less than 0.05) of rectal temperature (Tre) during exercise (prehypertonic 40.9 degrees C vs. no infusion 40.4 degrees C; hypertonic 40.8 degrees C vs. isotonic infusion 40.4 degrees C), but not at rest. Increasing the [Na+] and osmotic concentrations above 170 meq/liter and 325 mosmol/kg, respectively, resulted in no additional increase in exercise Tre. Water consumption during exercise decreased (P less than 0.05) plasma [Na+], osmolality, and the equilibrium level of Tre to control levels. There was no effect of changes in plasma volume (PV) of +/- 8% on the time course, equilibrium level, or change in Tre during exercise. At the end of exercise, there were moderate correlations (P less than 0.01) between Tre and [Na+] (r = 0.51) and Tre and osmoti (r = 0.52) concentrations. It was concluded that a) the exercise Tre responses of the dog respond quantitatively like man to elevated plasma [Na+] and osmolality, b) the Tre levels are not influenced by changes in PV, and c) water intake significantly reduces the ion-osmotic hyperthermia.

Animals↗
PubMed1975

Adrenergic responses to sustained handgrip in patients with juvenile-onset-type diabetes mellitus.

1. The response of plasma noradrenaline, arterial blood pressure and heart rate to sustained handgrip at 30% of maximal voluntary contraction was studied in patients with long-term juvenile-onset-type diabetes millitus and healthy subjects of comparable age. 2. There was no significant difference between the intensity and duration of handgrip in diabetic patients and healthy subjects. 3. Sustained handgrip produced an increase in plasma concentration of noradrenaline both in diabetic and healthy subjects but the response in the diabetic subjects was significantly less. 4. The increase in systolic blood pressure during handgrip was significantly greater in diabetic subjects than in normal subjects. The increases in diastolic and mean blood pressure did not differ significantky. 5. The increase in heart rate during handgrip was greater in healthy subjects than in diabetic subjects. The response was smaller in diabetic patients with retinopathy than in the patients without retinopathy. 6. The sustained handgrip test may be useful for the diagnosis of abnormal sympathetic nervous system and haemodnynamic responsiveness in diabetic patients.

Adolescent↗
PubMed1975

Plasma catecholamines and renin activity in response to exercise in patients with essential hypertension.

1. The effect of physical exercise on blood pressure, plasma catecholamines and plasma renin activity was studied in fourteen patients with essential hypertension and in eight healthy subjects. 2. Resting plasma noradrenaline and adrenaline and plasma renin activity of the hypertensive patients did not differ from those of the control subjects. 3. In response to graded exercise producing successive heart rates of 120, 140 and 160 beats/min, significantly greater increases of blood pressure were found in the patients than in the control subjects. 4. Plasma noradrenaline increased significantly in both groups at all levels of exercise, the responses being significantly greater in the hypertensive patients. 5. The mean arterial blood pressure was significantly correlated with plasma noradrenaline concentration in the control subjects but not in the hypertensive patients. 6. In the hypertensive group plasma adrenaline increased significantly after exercise at all work loads whereas, in the control group, significant increase occurred only at the highest work load. The differences in the response of the two groups were significant at each work load. 7. Plasma renin activity increased significantly after exercise at the heart rate of 120 beats/min, both in the hypertensive patients and in the control subjects. The magnitude of the response was similar in the two groups.

Adult↗