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Biomedical subjects

G L Dohm

Publications and source records attributed to G L Dohm.

At least 127 records · Page 7Linked to original sources
PubMed1982

Increased excretion of urea and N tau -methylhistidine by rats and humans after a bout of exercise.

This study was undertaken to investigate whether an exercise bout increases muscle protein degradation and amino acid catabolism. The excretion of urea and N tau -methylhistidine before and after an exercise bout was determined for both rats and human subjects. The rats ran on a treadmill until they could no longer run. Two groups of human subjects completed strenuous exercise bouts: one group (runners) ran 10-12 miles while the other group (weight lifters) performed a standard power lift routine that lasted approximately 1 h. In rats, urea excretion was elevated for the first 12 h after the exercise bout whereas N tau -methylhistidine excretion was elevated for 48 h following exercise. The increased N tau -methylhistidine excretion after exercise supports previous reports of increased protein degradation in the perfused hindquarter and increased levels of essential amino acids in muscle, liver, and plasma of exercised rats. In human subjects, both running and weight lifting resulted in increased excretion of urea and N tau -methylhistidine. The results of the present study support the hypothesis that muscle protein breakdown and amino acid catabolism are increased by exercise.

Animals↗
PubMed1981

Influence of exercise on free amino acid concentrations in rat tissues.

Levels of free amino acids in muscle, liver, and plasma were measured in rats that had either swum (1 or 2 h) or run (until exhausted). Exercise lowered alanine levels in all three tissues except for liver of exhausted rats. Exercise decreased the plasma levels of the acidic amino acids and their amides. Glutamate and glutamine levels were depressed in muscle, and the glutamine level was lowered in liver by exercise. Aspartate concentration was lowered by exercise in liver but elevated in muscle. The branched-chain amino acids were generally elevated by exercise as were tyrosine, phenylalanine, methionine, and lysine. Plasma 3-methylhistidine concentration was also elevated by an exercise bout. The changes observed in the amino acid contents of muscle, liver, and plasma are consistent with the increase in protein degradation during exercise that we previously reported. The lowered levels of some amino acids (e.g., alanine, glutamine, glutamate) seem to suggest that amino acid catabolism and/or gluconeogenesis is increased by exercise.

Amino Acids↗
PubMed1981

The ovariectomized female rat as a model animal for the study of adaptation to endurance training.

The effect of a 6-week endurance training program on food consumption and weight gain was investigated in intact and castrated male and female rats. Training decreased on weight gain and food consumption in both intact and castrated male rats. Intact female rats increased food consumption during training and had larger lean body weights than untrained-intact females at the end of the training program. However, the trained-ovariectomized rats consumed the same amount of food as the untrained-ovariectomized group and had similar lean body weights at the end of the training program. Thus, the ovariectomized female rat appears to be a good model for the study of adaptation to endurance training.

Adaptation, Physiological↗
PubMed1980

Effect of exercise on synthesis and degradation of muscle protein.

Several reports have shown that amino acid utilization via oxidation and gluconeogenesis is increased during exercise. The purpose of this study was to investigate whether these changes are accompanied by alterations in protein synthesis and degradation in the muscle of exercising rats. One group of rats was made in swim for 1h and then protein synthesis and protein degradation were measured in a perfused hemicorpus preparation. Protein synthesis was decreased and protein degradation was increased in exercised rats compared with sedentary control rats. Exercise also decreased amino acid incorporation by isolated polyribosomes from muscle. Measurement of several muscle proteinase activities demonstrated that exercise had no effect on alkaline proteinase or Ca2+-activated proteinase. However, the free (unbound) cathepsin D activity was elevated in muscle of exercised rats, whereas the total activity of catepsin D was unchanged. This increase in the proportion of free cathepsin D activity suggests that lysosomal enzymes may be involved in the increased protein degradation that was observed.

Animals↗
PubMed1980

Supplemental dietary carnitine and lipid metabolism in exercising rats.

Rats were physically trained by treadmill running and fed normal, high fat, or identical diets supplemented with 1.0% D,L-carnitine. Fatty acid oxidation, stimulated by exercise and/or by a high fat diet was studied to determine if it might be further augmented by supplemental dietary carnitine. Fatty acid oxidation in vitro or in vivo was unaffected by carnitine feeding. Carnitine feeding was associated with an increase in heart and muscle palmitylcarnitine acyltransferase activity and reduced serum cholesterol in trained rats fed the high fat diet. Under the conditions of this study, supplemental dietary carnitine did not greatly alter glyceride synthesis, lipolysis, or fatty acid oxidation, which indirectly indicates that the increased demands for fatty acid oxidation resulting from exercise or from fat feeding are adequately supported by endogenous levels of carnitine.

Animals↗
PubMed1978

Effect of sucrose on lipogenesis of rats chronically treated with ethanol.

The effect of chronic ethanol administration with and without sucrose on the lipogenic enzymes of liver and adipose tissue of rats was studied. Ethanol markedly influenced the adipose lipogenic enzymes at 28 days. Sucrose caused a 2-10fold increase in lipogenic enzymes of both adipose and liver.

ATP Citrate (pro-S)-Lyase↗
PubMed1977

Adaptation of protein metabolism to endurance training. Increased amino acid oxidation in response to training.

This study was conducted to investigate alterations in excretion of urea and total nitrogen after6-8 weeks of daily exercise and to establish if the capacity for amino acid oxidation in muscle is influenced by endurance training. Urea nitrogen excretion was increased in trained compared with untrained rats and nitrogen balance was less positive in trained than in untrained rats. Increased [14C]leucine oxidation with training was observed both in vivo and in vitro. The results of this study demonstrate that amino acid catabolism is increased during exercise training and that the muscle enzymes involved in leucine oxidation adapt to endurance training in a manner similar to the enzymes of carbohydrate and fat catabolism.

Adaptation, Physiological↗