Effects of nicardipine and other Ca2+-antagonists on catecholamine transport into chromaffin granule membrane vesicles.

: Nicardipine (10(-7)-2 X 10(-5) M) inhibited the transport of noradrenaline into chromaffin granule membrane vesicles in a concentration-dependent manner. This inhibitory effect of nicardipine was found to be appreciably stronger than that of other Ca2+-antagonists(diltiazem, nifedipine and verapamil) and was not due to the blockade of Ca2+-channel in the granule membranes.