Journal of Applied Physiology, Vol 53, Issue 2 448-454, Copyright © 1982 by American Physiological Society
Metabolic and cardiovascular adaptations in trained hypophysectomized rats
J. G. Edwards, D. D. Lund, T. G. Bedford, C. M. Tipton, R. D. Matthes and P. G. Schmid
Metabolic and cardiovascular changes resulting from acute and chronic
exercise were examined in male Sprague-Dawley rats assigned to sham-control
or hypophysectomized groups. Two weeks after surgery, the hypophysectomized
rats had decreased their maximum oxygen consumption (VO2 max) and heart
rate values by 4 ml X min-1 X kg-1 and 142 beats X min-1, respectively.
Twenty weeks later, hypophysectomy was associated with a 22 ml X min-1 X
kg-1 decrease in VO2 max and a 215 beat X min-1 decline in their maximal
heart rates when compared with sham-control means. Endurance training was
responsible for the significantly higher O2 consumption values.
Additionally, trained animals exhibited longer run times, higher muscle
cytochrome oxidase activity, and reduced food consumption. Measurements of
right atrial choline acetyltransferase (CAT) activity and [3H]quinuclidinyl
benzilate (QNB) binding revealed significantly higher CAT values and fewer
muscarinic receptors. However, training had no significant effect on
resting blood pressure, blood pressure changes with conditions of lower
body negative pressure, muscle glycogen concentrations, CAT levels and QNB
binding of the left atrium and ventricular regions, or receptor density.
These results indicated that many of the adaptations that are
characteristic of normal populations can occur in the absence of the
hormones from the pituitary gland.
