Adrenergic Analysis of Extracellular and Intracellular Lactate and H+Dynamics after Strenuous Exercise in the Starry Flounder Platichthys stellatus

Abstract

Adrenergic blockade with a selective a antagonist (yohimbine) and β antagonist (propranolol) was employed to test whether catecholamine mobilization was involved in lactate and acidic equivalents (H⁺) dynamics following strenuous exercise in chronically cannulated starry flounder. In control fish (not blocked) sampled repetitively for 8 h after exercise, arterial [lactate] remained characteristically low (<2 mmol/liter), and acid-base, hematological, and glucose changes were similar to those seen in other studies. Neither α nor β blockade immediately after exercise nor β blockade before exercise had significant influence on most responses, though hyperglycemia was inhibited by α blockade and prolonged by β blockade. Blood [lactate] was also marginally elevated, and red blood cell (RBC) swelling was reduced by β antagonism. A second series involving single-terminal sampling of cannulated flounder demonstrated that RBC intracellular pH (pHi), [NTP], and arterial PO₂ remained unchanged in the face of severe ...