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H G Schuler

Publications and source records attributed to H G Schuler.

27 records · Page 2Linked to original sources
PubMed1985

Aerobic capacity, obesity, and atherosclerotic risk factors in male adolescents.

Correlations between aerobic capacity, obesity, and atherosclerotic risk factors were evaluated in adolescents with low-to-moderate levels of physical fitness. Subjects with higher levels of fitness had a more favorable risk profile with decreased body mass index, lower systolic and diastolic blood pressure and plasma triglyceride levels, and higher plasma high-density lipoprotein-cholesterol levels. Simple linear regression analysis revealed an association between body mass index and blood pressure, plasma triglyceride and plasma high-density lipoprotein-cholesterol. The level of aerobic fitness as determined by exercise duration was also associated with the same atherosclerotic risk factors. However, multiple linear regression analysis demonstrated that body mass index provided the largest explanation, by those variables examined, of the interindividual variance in blood pressure, plasma triglyceride, and high-density lipoprotein-cholesterol. Aerobic fitness contributed only minimally to the variation in these risk factors. These findings suggest that if aerobic conditioning is used to modify atherosclerotic risk factors, it should be accompanied by a reduction in weight in adolescents with low-to-moderate levels of physical fitness.

Adolescent↗
PubMed1983

Fatty acid and glucose utilization in isolated, working newborn pig hearts.

The effects of exogenous fatty acids on glucose uptake were assessed in isolated, working newborn pig hearts in which great vessel pressures were controlled (mean 55 mmHg) and oxygenated nutrient buffer was recirculated through the heart for 30 or 60 min. When palmitate (1.5 mM) or octanoate (1.0 mM) were added to buffer containing 10 mM glucose and 100 mU insulin/ml, glucose uptake, as measured by 3H2O production from D-[2-3H]glucose, was suppressed to less than one-half that observed when glucose alone was present. Increased tissue levels of glucose 6-phosphate, fructose 6-phosphate, and citrate following perfusion in the presence of exogenous fatty acids were consistent with decreased glycolytic activity due to inhibition of phosphofructokinase. Measurements of carnitine in perfused and unperfused hearts indicated that total carnitine levels in neonatal hearts are similar to those of adult pigs. Increased tissue levels of long-chain acyl carnitine, acetyl carnitine, and citrate in hearts perfused with palmitate and glucose in combination with extensive fatty acid uptake and marked suppression of glycolysis indicated that the newborn pig heart is capable of utilizing fatty acids as a primary energy source.

Animals↗
PubMed1983

Fatty acid and glucose utilization in isolated, working fetal pig hearts.

Fatty acid uptake and the effects of long- and short-chain fatty acids on glucose utilization were assessed in isolated perfused fetal pig hearts (0.9 gestation) in which oxygenated nutrient buffer was pumped from both ventricles at controlled pressure (55 mmHg, mean arterial pressure) and heart rate (180 beats/min). When either 1.5 mM palmitate or 1.0 mM octanoate was added to buffer containing 10 mM glucose and insulin (100 microU/ml), glucose uptake, as measured by 3H2O production from D-[2-3H]glucose, was suppressed when compared with glucose uptake in the absence of fatty acid. Increased tissue concentrations of glucose 6-phosphate, fructose 6-phosphate, and citrate in hearts perfused with buffer containing octanoate indicated active beta-oxidation and inhibition of phosphofructokinase activity when compared with hearts perfused with glucose alone. In contrast, hearts perfused with buffer containing palmitate showed no increases in these metabolic intermediates. These results suggest that suppression of glucose uptake in the presence of long-chain fatty acid was not the result of phosphofructokinase inhibition but may result from inhibition of glucose transport by palmitate. Determinations of tissue concentrations of free carnitine and carnitine derivatives indicated that, although palmitate underwent esterification to long-chain acyl carnitine in the fetal heart, it failed to undergo extensive beta-oxidation.

Animals↗
PubMed1982

Perinatal changes in mitochondrial respiration of the rabbit heart.

Oxidative metabolism and citrate synthase activity during the perinatal period were assessed in isolated rabbit heart mitochondria at 27 days' gestation (27 dpc), 1 day postpartum (1 dpp) and 10 dpp. Oxygen consumption was measured during state 3 and state 4 respiration using the following substrates: glutamate, alpha-ketoglutarate, pyruvate/malate, succinate/rotenone, acetate, palmitylcarnitine, and palmityl CoA/carnitine. Results obtained from fetal and neonatal animals were compared to values obtained from adult left and right ventricles. Rates of state 3 oxygen consumption per milligram mitochondrial protein using tricarboxylic acid cycle intermediates or palmitylcarnitine were higher in both 1 and 10 dpp animals than in either left or right ventricles. Respiratory activity per milligram mitochondrial protein using these substrates was similar in 27 dpc fetuses and adult left ventricles. The rate of oxidation of palmityl CoA was lower in fetal mitochondria than in adult left ventricle, indicating that the capacity for conversion of long-chain fatty acyl CoA to acylcarnitine necessary for transport of fatty substrates into the mitochondria is decreased in fetal hearts. Increases in myocardial citrate synthase corresponded to increases in mitochondrial mass reported by other investigators.

Animals↗
PubMed1981

Carbohydrate metabolism in isolated, working newborn pig heart.

Metabolic activity of the newborn pig heart was observed by means of a preparation that allowed isolated hearts to perform a physiologic work load. A 10-min period of retrograde aortic perfusion was followed by 60 min of recirculating perfusion in which bicarbonate buffer was infused into the right atrium and ejected from both ventricles at measured pressures and flow rates. The buffer was supplemented with either glucose (10 mM), lactate (20 mM), or pyruvate (20 mM), or was unsupplemented. Pressure development and ventricular outputs were stable through 60 min of perfusion with glucose, pyruvate, or lactate supplementation. Myocardial high-energy phosphate and glycogen contents were also stable. In hearts perfused without substrate supplementation, mechanical performance deteriorated after 30 min. Rates of substrate uptake and oxygen consumption indicated that either glucose, lactate, or pyruvate could serve as a primary source of metabolic energy. Minimal lactate production was observed when either glucose or pyruvate were present. These findings indicate that, despite recent emergence from the relatively hypoxic intrauterine environment, the well-oxygenated newborn pig heart did not depend on anaerobic metabolism of glucose for energy production at physiologic work loads.

Adenosine Triphosphate↗