Human neonatal red blood cells. An experimental model for the study of calcium-activated potassium channel refractoriness.

Abstract

To study some characteristics of calcium-activated potassium channels free from plasma membrane lipid perturbations, neonatal red blood cells were selected. To this end, cells not previously treated (ATP depletion and/or reversible lysis) were exposed to the ionophore A23187 in a NO3 medium with calcium. The net efflux of potassium from the cells was studied. Preincubation in a medium devoid of potassium induced a significant decrease only in the rate constant of potassium flux. The data suggest that, in the absence of plasma membrane lipid impairment, changes in internal sites reactivity with calcium ions of channel proteins would be involved in the refractoriness. This would be at variance with channel density modifications.