Effect of simulated ischemia- reperfusion on I_f in sinoatrial node cells and the intervention of KATP channel opener

摘要

Objective: To study the effect of simulated ischemia-reperfusion (I/R) on I_f of sinoatrial node (SAN) cells and the intervention of KATP channel opener Pinacidil. Methods: The SAN cells of the neonatal rats were detached and purified 2 d before the experiment. The experimental animals were randomly divided into the control group, group of simulated I/R, group intervened with KATP channel opener Pinacidil (P+ I/R) and group intervened with KATP channel blocking agent 5-HD (5-HD + P + I/R & 5-HD + I/R) . The I_f density of each group was measured by technique of routine whole cell patch clamp and multiple- catheter perfusion system and the I_f activated curve in each group was drawn. Results: ①Under different directive potentials, the I_f density of the SAN cells in I/R group increased significantly, compared with that in the control group ( P < 0.01) ; that in P + I/R group decreased significantly, compared with that in I/R group ( P < 0.01 ); the I_f density values in 5-HD + P + I/R group and 5-HD + I/R group increased significantly, compared with that in P + I/R group, but showed no significant difference with that in I/R group. ②Compared with that in the control group, the I_f activated curve of the SAN cells moved rightwards under ultimate activating potential, half of which was from - 108.0 +- 12.4 to - 89.5 +- 7.2 mV ( P < 0.01 ); compared with that in I/R group, I_f activated curve of the SAN cells moved leftwards under ultimate activating potential, half of which was the range from - 99. 5 +- 10. 8 mV ( P < 0.05); KATP channel blocking agent 5-HD could block the effect of Pinacdil on I_f activated curve. Conclusion: KATP channel opener Pinacidil can antagonize the effect of simulated I/R on the I_f of SAN cells, which may be beneficial to the maintenance of the relative stability of ion steady state and electrophysiological activities under condition of simulated I/R.