Carlton P. Smith

Changes in tissue protein levels as a result of endurance exercise.

Abstract We previously reported that endurance training increases amino acid catabolism. In this study, the effects of an acute endurance exercise bout on tissue protein levels and urea excretion have been investigated. Exhaustive exercising of trained rats resulted in an increase in ammonia excretion but there was no significant change in urea excretion. Protein levels of muscle and liver were significantly decreased by an exhaustive bout of exercise. In muscle, both the soluble and myofibrillar protein fractions were decreased in exhausted rats. These results demonstrate that during exercise there is a net loss of protein in muscle and liver.

Lipid content and fatty acid composition of heart and muscle of the BIO 82.62 cardiomyopathic hamster.

Microscopic and analytical studies of the lipids in the heart and muscle of the BIO 82.62 myopathic hamsters and agematched normal animals at the average ages of 33, 67, and 108 days were performed. Microscopic examinations did not show increased lipid depositions in the hearts of the diseased animals as was found in the BIO 14.6 strain. No consistent differences in the lipid content of the cardiomyopathic hamsters (BIO 82.62) and age-matched controls were observed in the three age groups except in the cholesterol content of muscle. Cholesterol increased significantly (P<0.01) in the 67 and 108 day old animals. This increase elevated the cholesterol/phospholipid ratio. Analysis of the fatty acid composition of triglycerides showed that the cardiomyopathic hamsters store more saturated fatty acids in both heart and muscle than do their normal counterparts. The abundance of more saturated fatty acids may imply that either the desaturation mechanism is altered in the diseased animals or that unsaturated fatty acids are preferentially utilized in other processes.

Effect of cocaine, ethanol or nicotine on ornithine decarboxylase activity in early chick embryo brain.

Fetal drug exposure causes multiple deficits in the developing child. For both humans and animal models, the single most common drug-related problem is fetal growth suppression. This defect is associated with significant perinatal morbidity and mortality and may also be related to significant behavioral problems appearing later in life. Studies focussed on the molecular mechanism of fetal drug effects in placental models are complicated by multiple interactions of the drug with mother, placenta and fetus. Using early (76-168 h) chick embryos as a non-placental model, and three common drugs of abuse (nicotine, ethanol and cocaine) it was found that each drug suppressed the peak in fetal brain ornithine decarboxylase (ODC) activity that normally occurs at 120 h of development. For each drug, the decrease in ODC activity at 120 h was followed by a small but significant increase in ODC. Thus, although the drug-treated embryos were smaller in size, they appeared to be undergoing compensatory growth and, in fact, became equal in weight to the vehicle-treated animals, if allowed to hatch.

Indomethacin stimulation of lipid peroxidation and chemiluminescense in rat liver microsomes.

Peroxidation of endogenous lipid by rat liver microsomes, coupled with oxidation of reduced nicotinamide adenine dinucleotide phosphate (NADPH) and measured as thiobarbituric acid reactive materials, is markedly stimulated in the presence of indomethacin [1-(p-chlorobenzyl)-5-methoxy-2-methyl-3-indole acetic acid] (0.1–1.0 mM). Concurrently, indomethacin enhances the lipolysis of membrane phospholipid containing arachidonic acid but has no effect on the rate of O2 uptake in these samples. The system generates a rapidly developed chemiluminescense (CL), the intensity and rate of development of which are related to indomethacin concentration. The microsomal CL generated in the presence of indomethacin is distinct from the previously reported CL in that the time required for maximum intensity development is a matter of seconds (20–180) rather than hours. The enhanced CL is believed to be due to an energy transfer reaction whereby a high energy species transfers energy to the indomethacin molecule, which, in turn, decays via chemiluminescense. An enhanced chemiluminescense was also observed when indomethacin was added to a lipoxidase system and superoxide generating system (xanthine oxidase). Based on inhibitor studies, the rapidly developed chemiluminescense of the microsomal system requires cytochrome P-450 in addition to NADPH and coordinated iron ions. The results indicate that the CL is related to neither hydroxyl free radical nor superoxide anion formation.

Glyceride metabolism in the myopathic hamster.

Analysis of plasma lipids of 30- and 185-day-old BIO 82.62 myopathic hamsters and age-matched normal controls revealed a decrease in only the concentration of cholesteryl esters of 185-day-old diseased animals. Measurement of lipoprotein lipase (LPL) activity in heart, muscle, and adipose tissue showed no difference between the activity of the enzyme in the heart and muscle of the cardiomyopathic hamsters and that of the age-matched controls. In adipose tissue, however, LPL activity was depressed in the diseased animals in both age groups. No difference was found in the activity of hormone sensitive lipase. Incorporation of sn[U-14C] glycerol-3-phosphate into total lipids was found to be depressed in homogenates of heart, muscle, and adipose tissue but unchanged in liver homogenates of diseased animals. It was concluded that the decrease in the capacity to synthesize glycerides, rather than limiting substrate concentrations, could be the cause of the decrease in the lipid content in some tissues of the cardiomyopathic hamster.

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.