AJP - Regulatory, Integrative and Comparative Physiology, Vol 255, Issue 3 395-R399, Copyright © 1988 by American Physiological Society
Correlation between catecholamine release and degree of acidotic stress in trout
Y. Tang and R. G. Boutilier
Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
Exhaustive exercise in freshwater (FW) and seawater (SW) rainbow trout
resulted in a marked and acute increase of plasma catecholamines.
Immediately after exercise, epinephrine and norepinephrine concentrations
in FW trout were 69 and 15 times the resting level, respectively; in SW
trout, they were 46 and 11 times the resting value, respectively. Over the
1st h of recovery, the magnitude of the catecholamine surge in FW animals
was about twice that of their SW counterparts. Correlated with this was an
extracellular pH disturbance in FW trout, which was approximately twice as
severe as in SW trout. Indeed, both the magnitudes and time courses of the
plasma catecholamine responses were matched to those of the acid-base
disturbances. Linear correlations were found to exist between the immediate
depression of blood pH and the corresponding increases in plasma
epinephrine and norepinephrine. We conclude that catecholamines are
released into the plasma in proportion to the magnitude of the acid-base
disturbance. The higher postexercise levels of plasma catecholamines in FW
trout vs. SW appear to be a response to the greater acid-base disturbance
in the FW animals.
