HUMAN NEONATAL RED-BLOOD-CELLS - AN EXPERIMENTAL-MODEL FOR THE STUDY OF CALCIUM-ACTIVATED POTASSIUM CHANNEL REFRACTORINESS

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