Original Article

Electrophysiological effects of m-nisoldipine and nisoldipine on papillary muscles of guinea pig

Rui-hai AN, Rui-rong HE


The effects of m-nisoldipine (m-Nis) and nisoldipine (Nis) on action potentials of papillary muscles in guinea pigs were studied using intracellular microelectrodes.
(1) APD and Vmaxs in normal papillary muscles were reduced by m-Nis and Nis. However, the APA, Vmaxf and overshoot were not affected. (2) In the partially depolarized papillary muscles, the APA, overshoot, Vmax and APD were depressed in a dose-dependent manner. The inhibitory effects of Nis on APA, APD50 and PPD were greater than those of the m-Nis. (3) There was a good correlation between APD50 and PPD derived from a linear regression. By the linear equation, PPD was easily calculated from APD50.

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