Effect of sanguinarine, a benzophenanthridine alkaloid, on frog skin potential difference and short circuit current

Sanguinarine, a benzophenanthridine alkaloid, causes a initial stimulation of frog skin short circuit current Isc when present in the mucosal bathing medium at 10(-4) M. The stimulation is accompanied by an increase in spontaneous potential difference (PD) and increase in D.C. resistance. No effects are seen with sanguinarine in the serosal bathing medium. The initial stimulation is followed by a decrease in Isc and PD, but a continued increase in resistance. In skins whose initial spontaneous PD is high, no initial stimulation in Isc and PD is seen; however, clamping these skins to a lower potential does not alter their initial inhibitory response to sanguinarine. Likewise, clamping the lower potential skins to higher potential does not alter their initial stimulatory response. Sanguinarine seems to be acting on the permeability barriers at the outer surface of the frog skin.