Effects of quinine on membrane potential and membrane currents in identified neurons of Helix pomatia.

In the neurons B1, B2 and B3 of Helix pomatia, a systemic administration of quinine elicited: (1) a depolarization accompanied by an increase in membrane resistance (RM), sometimes preceded by a hyperpolarization associated with a decrease in RM; (2) a diminution in amplitude of action potentials and of afterhyperpolarization; (3) a reversible decrease of the amplitude of the inward current with a shift of the maximum amplitude and of the reversal to more negative potential values; (4) no change in the steady state inactivation curve of the inward current; and (5) a partly irreversible depression of the early outward current and of the late outward currents.