Journal of Applied Physiology, Vol 72, Issue 4 1285-1290, Copyright © 1992 by American Physiological Society

ARTICLES

Changes in plasma and erythrocyte K+ during hypercapnia and different grades of exercise in trout

O. B. Nielsen and G. Lykkeboe
Department of Zoophysiology, University of Aarhus, Denmark.

Trout were exposed to hypercapnia, two levels of aerobic exercise, or three successive periods of supramaximal exercise to evaluate the effects on erythrocyte and plasma K+. During aerobic exercise, plasma K+ increased slightly with the intensity of work, while no change was found in the erythrocyte K+ content. In contrast, both hypercapnia and supramaximal exercise induced a net erythrocyte K+ uptake. This uptake changed to a net loss of K+ as arterial pH and hemoglobin-bound oxygen saturation returned to control values during recovery. The maximal rates of net K+ uptake found during hypercapnia and supramaximal exercise corresponded to 195 and 350 mumol.kg fish-1.h-1, respectively, and the maximal rates of net K+ loss found during recovery corresponded in both cases to approximately 130 mumol.kg fish-1.h-1. Hypercapnia had only a minor effect on plasma K+, but return to normocapnic conditions induced a 0.8 mM rise in plasma K+. Of this increase, approximately 70% could be accounted for by the simultaneous net release of erythrocyte K+. Each period of supramaximal exercise induced an elevated plasma K+ level, resulting in accumulation of plasma K+ despite slight decreases in plasma K+ in between the exercise periods. At the same time the net erythrocyte K+ uptake caused an estimated reduction in plasma K+ of 1.5 mM. It is concluded that both hypercapnia and supramaximal exercise cause profound net changes in the erythrocyte K+ content with significant effects on plasma K+.

This article has been cited by other articles:

				C. E. Molina, H. Gesser, A. Llach, L. Tort, and L. Hove-Madsen Modulation of membrane potential by an acetylcholine-activated potassium current in trout atrial myocytes Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2007; 292(1): R388 - R395. [Abstract] [Full Text] [PDF]

				L. M. Hanson, S. Obradovich, J. Mouniargi, and A. P. Farrell The role of adrenergic stimulation in maintaining maximum cardiac performance in rainbow trout (Oncorhynchus mykiss) during hypoxia, hyperkalemia and acidosis at 10{degrees}C J. Exp. Biol., July 1, 2006; 209(13): 2442 - 2451. [Abstract] [Full Text] [PDF]

				J. Nielsen and H Gesser Effects of high extracellular [K+] and adrenaline on force development, relaxation and membrane potential in cardiac muscle from freshwater turtle and rainbow trout J. Exp. Biol., January 1, 2001; 204(2): 261 - 268. [Abstract] [PDF]

				O. M. Sejersted and G. Sjogaard Dynamics and Consequences of Potassium Shifts in Skeletal Muscle and Heart During Exercise Physiol Rev, October 1, 2000; 80(4): 1411 - 1481. [Abstract] [Full Text] [PDF]

				M. Berenbrink, S. Volkel, N. Heisler, and M. Nikinmaa O2-dependent K+ fluxes in trout red blood cells: the nature of O2 sensing revealed by the O2 affinity, cooperativity and pH dependence of transport J. Physiol., July 1, 2000; 526(1): 69 - 80. [Abstract] [Full Text] [PDF]

				J. Gibson, A. Cossins, and J. Ellory Oxygen-sensitive membrane transporters in vertebrate red cells J. Exp. Biol., January 5, 2000; 203(9): 1395 - 1407. [Abstract] [PDF]

				S Volkel and M Berenbrink Sulphaemoglobin formation in fish: a comparison between the haemoglobin of the sulphide-sensitive rainbow trout (Oncorhynchus Mykiss) and of the sulphide-tolerant common carp (Cyprinus Carpio) J. Exp. Biol., January 3, 2000; 203(6): 1047 - 1058. [Abstract] [PDF]