[The identification and properties of chloride potential-dependent channels in the membrane of secretory cells].

Outward current of the salivary gland cells membrane of chironomus larva activated by the displacement of the membrane potential to the region of positive values has been registered by the voltage-clamp method under conditions of intracellular dialysis in the presence of the chloride transmembrane gradient. Activation threshold of the current is about +20 mV. Subsequent displacement of the membrane potential to the region of positive values causes an increase of the current. Time constant of the current activation is (573 +/- 34.4) ms. The current decreases with the reduction of extracellular chloride concentration, under the influence of tannin acid and temperature lowering, under conditions of alkaline medium. The current increases due to Hg2+ ions and lowering of the outward solution pH. Thus, the membrane of secretory cells contain high-threshold potential-dependent chloride channels which are characterized by the following selectivity series: Br- greater than Cl- greater than NO3- greater than SO4(2-) greater than F- greater than HCOO- greater than CH3COO-.