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To assess the roles of decrements in insulin and increments in glucagon in the prevention of hypoglycemia during moderate exercise (approximately 60% peak O2 consumption for 60 min), normal young men were studied during somatostatin infusions with insulin and glucagon infused to 1) hold insulin and glucagon levels constant, 2) decrease insulin, 3) increase(More)
BACKGROUND Transmural heterogeneity in ventricular repolarization demonstrated in vitro has been difficult to confirm in vivo. Whether this discrepancy reflects a physiological phenomenon or a methodological problem remains a vivid matter of debate despite a plethora of experimental work. Therefore, we have measured the relevant electrophysiological(More)
The sympathochromaffin system, probably sympathetic neural norepinephrine, plays a primary role in the prevention of hypoglycemia during exercise in humans. Our previous data indicated that changes in pancreatic islet hormones are not normally critical but decrements in insulin, increments in glucagon, or both become critical when catecholamine actions are(More)
We assessed simplified approaches to measurement of steady-state norepinephrine (NE) kinetics (short, nonprimed infusions of [3H]NE or of unlabeled NE and arterialized venous sampling), then reexamined the kinetic mechanism(s) of the age-associated increase in plasma NE, and tested the hypothesis that the latter is the result of a sedentary lifestyle. We(More)
Advanced age is a risk factor for hypoglycemia caused by sulfonylureas (and insulin) used to treat diabetes mellitus. Therefore, we hypothesized that there is an age-associated impairment of glucose counterregulation and further that this is the result of a sedentary life-style. To test these hypotheses, glycemic and neuroendocrine responses to(More)
To assess the role of catecholamines in the prevention of hypoglycemia during moderate exercise (approximately 60% peak O2 consumption for 60 min), normal humans were studied with combined alpha- and beta-adrenergic blockade and with adrenergic blockade while changes in insulin and glucagon were prevented with the islet clamp technique (somatostatin(More)
To determine the role of epinephrine in glycogenolysis during high-intensity exercise, rats were adrenodemedullated (ADM) or sham operated (SHAM) and run for either 30 min at 38 m/min or for 5 min at 27, 38, or 48 m/min up a 15% grade. At the end of exercise the rats were anesthetized by intravenous injection of pentobarbital sodium. Liver, blood, and(More)
To determine the role of adrenal medullary hormones in controlling the rate of liver glycogenolysis during exercise, adrenodemedullated (ADM) and sham-operated (SO) rats were run on a rodent treadmill at 21 m/min up a 15% grade for 0, 30, or 60 min. Rats were anesthetized by intravenous injection of pentobarbital sodium, and liver, muscle, and blood were(More)
To determine the possibility of a threshold concentration of plasma epinephrine that stimulates liver glycogenolysis during exercise, adrenodemedullated (ADM) and sham-operated (SHAM) rats were infused with saline or epinephrine at rates that produced plasma concentrations ranging between 0.01 ng/ml (0.06 nM) and 4.3 ng/ml (23.7 nM). During the infusion(More)
In this experimental study we examined the effects of listening to relaxation-type music on self-reported anxiety and on selected physiologic indices of relaxation in patients with suspected myocardial infarction. Seventy-five patients were randomly assigned to one of two experimental groups, one listening to music and the other to "white noise," or to a(More)