Modulation by external Ca super(2+) and nicardipine of Ca super(2+) influx and cytosolic concentration in human erythrocytes

• Published in: Biochemical and biophysical research communications Vol. 173; no. 3; pp. 954 - 960
• Main Authors: David-Dufilho, M, Astarie, C, Pernollet, M G, Bergougnan, L, Comte, A, Dubray, C, Devynck, MA
• Format: Journal Article
• Language: English
• Published: 01.01.1990
• ISSN: 0006-291X

Variations of Ca super(2+) influx and cytosolic free Ca super(2+) concentration ((Ca super(2+)) sub(i)) were investigated in human erythrocytes. When external Ca super(2+) concentration ((Ca super(2+)) sub(o)) rose from 1 to 2 mM, the initial rate of Ca super(2+) influx nearly doubled whereas (Ca super(2+)) sub(i) increased only by 15%. Nicardipine dose-dependently decreased both initial rate of Ca super(2+) influx and (Ca super(2+)) sub(i). The less marked changes in (Ca super(2+)) sub(i) than in Ca super(2+) influx indicate a partial adjustment of the Ca super(2+) extruding-pump activity to of Ca super(2+) influx. In vivo administration of nicardipine reduced (Ca super(2+)) sub(i) only when its initial value exceeded 80nM and prevented the rise in (Ca super(2+)) sub(i) induced by the increase in (Ca super(2+)) sub(o).