Role of N-type calcium channels in autonomic neurotransmission in guinea-pig isolated left atria

Abstract

1. Calcium entry via neuronal calcium channels is essential for the process of neurotransmission. We investigated the calcium channel subtypes involved in the operation of cardiac autonomic neurotransmission by examining the effects of selective calcium channel blockers on the inotropic responses to electrical field stimulation (EFS) of driven (4 Hz) guinea-pig isolated left atria. In this tissue, a previous report (Hong & Chang, 1995) found no evidence for N-type channels involved in the vagal negative inotropic response and only weak involvement in sympathetic responses. 2. The effects of cumulative concentrations of the selective N-type calcium channel blocker, omega-conotoxin GVIA (GVIA;..