AJP - Regulatory, Integrative and Comparative Physiology, Vol 242, Issue 3 306-R310, Copyright © 1982 by American Physiological Society
Catecholamine release and blood pressure changes induced by exercise in dogfish
D. F. Opdyke, R. G. Carroll and N. E. Keller
Plasma norepinephrine (NE), epinephrine (E), and potassium (K+) were
measured before, during a 3-min bout of exercise, and at intervals after
exercise in Squalus acanthias. The dorsal aortic pressure response
following 1 min of exercise was observed in another series of experiments.
Plasma E, NE, and K+ increased significantly and progressively during the
exercise period and for 2 min after exercise. Plasma E increased
significantly during the 1st min; NE during the 2nd min; but K+ did not
increase significantly until the 3rd min of exercise. Blood pressure
decreased significantly during 1 min of exercise but increased over control
level within 4 min after the end of exercise coincident with the peak of
plasma E and NE concentrations. Plasma NE, E, and blood pressure decreased
slowly in parallel fashion during the 37-min postexercise period of
observation. Increased plasma K+ from skeletal muscle is probably not the
primary stimulus for early catecholamine release in exercising dogfish, but
increased plasma K+ does contribute to releasing and maintaining plasma NE
and E levels in the postexercise period. This results in a sustained
pressor effect that promotes blood flow and aids in metabolic recovery.
