Vasopressin modulates membrane properties of taste cells isolated from bullfrogs.

The effect of arginine vasopressin (AVP) on the membrane properties was analyzed in isolated bullfrog taste cells using a perforated whole-cell patch-clamp technique. AVP (100 nM) induced three kinds of responses in rod-type taste cells: appearance of inward current, inhibition of voltage ramp-induced outward current and enhancement of the outward current. The Ca(2+)-ionophore ionomycin (3 microM) also induced inward current in taste cells. A membrane-permeable cAMP analog, 8-CPT-cAMP (0.3 mM) inhibited voltage ramp-induced outward current in some rod cells, but enhanced the current in other rod cells. The results suggest that AVP may increase either intracellular Ca2+ level or cAMP level in taste cells, modulating the membrane excitability.