Abstract: Aim: To study the effects of rhynchophylline (Rhy) on the L-type calcium channels in freshly dissociated cortical neurons of Wistar rats during acute hypoxia. Methods: Cell-attached configuration of patch clamp technique. L-type calcium channel was activated by stepping from-40 mV to 0 mV. Results: The results showed that the L-type calcium channels of cortical neurons were activated by acute hypoxia. The mean open time of the channel was increased, the mean close time decreased and the open-state probability raised during acute hypoxia. Rhy (15 and 30 μmol·L^-1) in concentration dependent manner blocked activity of the channels. The drug shortened the mean open time of the channels from 8.87 ms to 3.03 ms and 2.23 ms (P<0.001), prolonged the mean close time from 9.23 ms to 38.84 ms and 54.43 ms (P<0.001), and decreased the open-state probability from 0.142 to 0.031 and 0.025 (P<0.001) under the hypoxia condition, respectively. The effects of Rhy were similar to but weaker than those of verapamil (15 μmol·L^-1). Conclusion: The study confirmed that Rhy has the blockade effects on L-type calcium channels in cortical neurons of rats during hypoxia, by which it protects the brain from hypoxic injury.

Key words: Patch clamp, Cortical neuron, Calcium, Ion channel, Rhynchophylline, Hypoxia