AJP - Regulatory, Integrative and Comparative Physiology, Vol 250, Issue 6 1060-R1064, Copyright © 1986 by American Physiological Society
Adrenergic influence on hormonal and hepatic metabolic response to exercise in rats
C. A. Tate, N. M. Scherer and G. Stewart
The adrenergic control of the hormonal and hepatic metabolic response to
exercise was studied in untrained fed male rats. Rats were injected
intraperitoneally with either saline, the alpha-adrenergic antagonist
phentolamine, or the beta-adrenergic antagonist propranolol 30 min before
exercise. The rats swam for 50 min in 34-35 degrees C water with a tail
weight (5% of body wt). Exercise resulted in a suppression of plasma
insulin in all treatment groups; however, plasma glucagon increased only in
the propranolol group. The liver glycogen content was decreased with
exercise only in the saline and propranolol groups. Likewise,
phosphorylating respiration of liver mitochondria isolated after exercise
was higher only in the saline and propranolol groups. Thus phentolamine
pretreatment blocked the liver glycogen depletion and the increased liver
mitochondrial phosphorylating respiration observed after exercise in fed
rats. The results suggest that alpha-adrenergic mechanisms are operant with
exercise and stimulate liver glycogenolysis and mitochondrial
phosphorylating respiration.
