Effects of metabolic acid-base disturbances and elevated catecholamines on the acid-base disequilibrium in the arterial blood of rainbow trout

Abstract

An extracorporeal circulation and stopflow technique were used to characterize the acid—base disequilibrium in the arterial (post-branchial) blood of rainbow trout, Oncorhynchus mykiss, after alteration of the blood pH through acid, base, or catecholamine infusion, or by inducing endogenous catecholamine release. Arterial blood was routed from the coeliac artery through an external circuit in which pH and the partial pressures of oxygen and carbon dioxide were monitored continuously. The stopflow condition was imposed by turning off the pump which drove the external loop. The results of this study support the prediction that blood acid—base status is one factor determining the size of the disequilibrium. Under control conditions, the arterial blood exhibited a statistically significant positive disequilibrium (increase in pH upon stopflow) of 0.02 ± 0.01 to 0.04 ± 0.01 units. Decreasing blood pH by the infusion of a fixed acid load ((NH4)2SO4) or by adrenergic activation of the red blood cell Na+/H+ antiporter increased the magnitude of the positive disequilibrium (0.11 ± 0.01 to 0.17 ± 0.02 units). © 1996 Wiley-Liss, Inc.