Enhancement of lanthanum (III) on sodium currents in acutely isolated hippocampal CA1 neurons of rat.

The effects of lanthanum (III) (La(3+)) on voltage-gated sodium channel currents (I (Na)) in freshly dissociated rat hippocampal CA1 neurons were studied using the whole-cell patch clamp techniques. La(3+) reversibly enhanced I (Na) in a concentration- and voltage-dependent manner. The 50% enhancement concentration (EC(50)) of La(3+) on I (Na) was 9.93 microM. In addition, 10 microM La(3+) shifted the steady state activation curve of I (Na) towards positive potential and the steady state inactivation curve towards negative potential without changing the slope factor. These results indicated that La(3+) could increase the amplitudes of I (Na) and change the activation and inactivation courses of I (Na) even in very low concentration.