Endocrine Regulation of Metabolism During Exercise
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The efficiency of hormonal stimulation on metabolic regulation not only depends on the plasma concentration of the hormones, their receptors, post-receptor, and second messenger systems, but also on the enzymatic and metabolic adaptation triggered by physical activity. Insulin and catecholamines, as well as the mechanisms, which elicit the metabolic response, will be discussed. The previous assumption of the insulin mediated glucose transport through the cell membrane after insulin receptor interaction and post-receptor activation is challenged by the function of the glucose transporter Glut 4 on the plasma and intracellular membranes. New findings on this subject, such as additive effects of insulin and exercise, will be reported. The exercise induced catecholamine overflow, which can exceed resting values by up to 50 fold, is attenuated by adrenoreceptor down-regulation, post-receptor adaptation, activation of second messenger systems, metabolic and renal clearance rates, as well as by the sulfconjugation of catecholamines. The metabolic regulation of carbohydrate-and lipid metabolism by insulin and catecholamines will be addressed.
KeywordsGlucose Uptake Insulin Receptor Glucose Transporter Glucose Transporter Glut Membrane Density
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