NITRENDIPINE IS A POTENT INHIBITOR OF THE CA2+-ACTIVATED K+ CHANNEL OF HUMAN ERYTHROCYTES

Nitrendipine, a classical blocker of L-type Ca2+ channels, is shown to be a potent inhibitor of the Ca2+-activated K+ channel of human erythrocytes. In erythrocytes suspended in a solution with physiological Na+ and K+ concentrations and in which the channel was activated using the Ca2+ ionophore ionomycin, nitrendipene inhibited K+(Rb-86(+)) influx with an I50, of around 130 nM. Similar results were obtained for K+(Rb-86(+)) efflux, and for K+(Rb-86(+)) influx into cells suspended in a high-K+ medium.