Potassium transport in lamprey ( Lampetra fluviatilis) erythrocytes: Evidence for K + channels

Abstract

1. 1. Unidirectional K + ( 86Rb) influx in lamprey red blood cells was studied under different conditions. 2. 2. The influx of 86Rb was markedly inhibited by 1 mM Ba 2+ when cells were incubated in saline containing 4 mM K +. In K +-free media, the influx rate constant of 86Rb was lower, and 1 mM Ba 2+ had no blocking effect. 3. 3. Treatment of the red cells with 0.1 mM ouabain in the absence of external K + resulted in the appearance of the component of 86Rb influx inhibited by 1 mM Ba 2+ quinine, TEA or amiloride. 4. 4. Similar results were obtained in red cells incubated in Na +-free media MgCl 2-sucrose. 5. 5. The results obtained provide evidence for the existence of K + channels in the red cell membrane of the lamprey. Under physiological conditions (in the presence of 4 mM K +) the total rate constant for the 86Rb influx in erythrocytes was about 1.9/hr, including ouabain-sensitive (0.6/hr), Ba 2+-sensitive (1.1/hr) and residual (0.2/hr) components.