The low-threshold Ca current in isolated amygdaloid neurons in the rat

Two types of voltage-dependent Ca currents were recorded from isolated rat amygdaloid neurons under single-electrode voltage-clamp. A low-threshold Ca current was elicited at -60 mV or more positive potentials and inactivated rapidly. At -30 mV or more positive potentials, a high-threshold Ca current was also activated. In steady-state inactivation curve of the low-threshold Ca current, the half-inhibition value (h0.5) was -71 mV. The low-threshold Ca current was inhibited by organic and inorganic Ca blockers in a dose-dependent manner. The inhibitory effect of these Ca blockers was completely reversible while that of flunarizine was partly so. It is concluded that the membrane and pharmacological properties of the low-threshold Ca channel in the rat amygdaloid neurons are quite similar to those in the hypothalamic neurons.