[Identification of depolarization-activated calcium flow in the secretory cell membrane]

The inward depolarization-activated current of the salivary gland cell membrane of the chironomus larva has been registered by the voltage-clamp method under conditions of the intracellular dialysis in the presence of the calcium transmembrane gradient only. An activation threshold of the current is about -50 mV, the current maximum is under -10 mV, reversion up to +10 mV leads to the current reduction. An increase in the extracellular Ca2+ concentration causes current amplification; the current decreases under the influence of verapamil, chlorpromazine, Mn2+ and Co2+. These results could indicate the existence of potential-dependent calcium channels in the secretory cell membrane.