Kinetic analysis of prepulse facilitation of calcium currents in hamster submandibular ganglion neurons.

Abstract

The calcium ion influx through voltage-dependent calcium channels (VDCCs) has a vital role in the control of neurotransmitter release and membrane excitability. The modulation of VDCCs controls the extent of calcium entry and thus provides a way of regulating neuronal function. Prepulse facilitation is a phenomenon in which a strong depolarizing pulse induces a form of the VDCCs that exhibits an increased opening probability in response to a given test potential that persists for several seconds after repolarization. In this study, we have studied the characterization of prepulse facilitation of VDCCs currents (Ica) in hamster submandibular ganglion (SMG) neurons, using whole-cell patch clamp recordings. In SMG neurons, application of a strong depolarizing prepulse caused a Ica. In 8 SMG neurons, rate of facilitation was 1.1 +/- 0.1. The greatest value of prepulse facilitation was obtained with prepulse to +100 mV, 10 ms duration in this neuron. The magnitude of facilitation was dependent on changing the interval between the -prepulse and the +prepulse and reached a maximum at a interval of 500 ms.