Journal of Applied Physiology, Vol 62, Issue 3 1040-1045, Copyright © 1987 by American Physiological Society
Neurohumoral and cardiopulmonary response to sustained submaximal exercise in the dog
P. C. Kirlin, M. D. Kittleson and L. E. Johnson
Neurohumoral, cardiovascular, and respiratory parameters were evaluated
during sustained submaximal exercise (3.2 km/h, 15 degrees elevation) in
normal adult mongrel dogs. At the level of activity achieved (fivefold
elevation of total body O2 consumption and threefold elevation of cardiac
output), significant (P less than 0.05) increases in plasma norepinephrine
and epinephrine concentration (from 150 +/- 23 to 341 +/- 35 and from 127
+/- 27 to 222 +/- 31 pg/ml, respectively) were present, as well as smaller
but significant increases in plasma renin activity and plasma aldosterone
concentration (from 2.2 +/- 0.3 to 3.1 +/- 0.6 ng X ml-1 X h-1 and from 98
+/- 8 to 130 +/- 6 pg/ml, respectively). Plasma arginine vasopressin
increased variably and insignificantly. The cardiovascular response (heart
rate, systemic arterial and pulmonary arterial pressures, left ventricular
filling pressure, and calculated total peripheral and pulmonary arteriolar
resistance) closely paralleled that of human subjects. Increased hemoglobin
concentration was induced by exercise in the dogs. The ventilatory response
of the animals was characterized by respiratory alkalosis. These data
suggest similarities between canine and human subjects in norepinephrine,
plasma renin activity, and plasma aldosterone responses to submaximal
exercise. Apparent species differences during submaximal exertion include
greater alterations of plasma epinephrine concentration and a respiratory
alkalosis in dogs.
