RESUMO
Aim This paper aims at investigating the effect of dofetilide on Na+/Ca 2+exchange in ventricular myocytes of adult guinea pigs. Methods Rapid enzymatic isolation procedure was performed to get single ventricular myocytes from adult guinea pigs. After the whole cell configuration was formed, a ramp voltage-clamp pulse depolarized from a holding potential of -40 mV to +60 mV, then hyperpolarized to -120 mV at a rate of 90 mV/s to record the Na+/Ca 2+ exchange current (I Na/Ca) and the influence of dofetilide from 0.03～1.0 ?mol?L -1. Result Dofetilide from 0.03～1.0 ?mol?L -1 concentration-dependently increased the I Na/Ca in both outward and inward mode. The EC 50 of dofetilide on I Na/Ca in outward and inward mode of NCE was 0.178 ?mol?L -1 (95% confidence interval was 0.040～0.787 ?mol?L -1) and 0.178 ?mol?L -1 (95% confidence interval was 0.038～0.842 ?mol?L -1), respectively. Conclusion Dofetilide concentration-dependently increased the outward and inward Na+/Ca 2+ exchange current in ventricular myocytes of adult guinea pigs.