RESUMO
Objective To evaluate the effects of remifentanil (RMF)on large conductance cal-cium-activated potassium channel (BKCa)and voltage-gated potassium channel (KV)activition currents in basilar arterial smooth muscle cells (BASMCs)of normotensive and hypertensive rats. Methods Spontaneously hypertensive rats (SHR)and homologous normotensive wistar-kyoto (WKY)rats,were used in this study.BASMCs were obtained freshly by the method of enzymolysis. Six basilar artery smooth muscle cells of each rat were chosen and analyzed.Outward current ampli-tude was recorded by the whole-cell patch clamp technique.The outward current amplitude under all stimulation voltage in set of step stimulation protocol before (basal level)and after administration of RMF (3×10-7mol/L)were recorded respectively and net current was calculated (net current=cur-rent amplitude after administration-basic value).With administration by concentrations cumulative method,the current amplitude under +60 mV stimulation voltage was separately recorded before (basic value)and after application of different concentrations of RMF (10-10,10-9,10-8,10-7, 10-6,10-5mol/L),then calculated current increasing rate and the half effective concentration (EC50)of RMF increasing current amplitude in BASMCs.Another six basilar artery smooth muscle cells of each rat were chosen and given RMF (3×10-7mol/L),and separately treated with BKCa channel blocker (tetraethylammonium,TEA)and Kv channel blocker (4-aminopyridine,4-AP),and then administrated the corresponding RMF mixture.The current amplitude was recorded after each dose.Results At 0,+20,+40 and +60 mV,the net current generated by RMF on both BASMCs of rats was successively and significantly increased (P <0.05).The increment rate of outward currents in BASMCs generated by 10-10,10-9,10-8,10-7RMF successively and significantly went upward (P<0.05).Compared to WKY rats,the half-effective concentration(EC50)of RMF increas-ing the current amplitude in BASMCs of SHR significantly rose(P<0.05).Compared with the base-line,the current amplitude in BASMCs of the two kind rats was significantly increased after adminis-tration of RMF,and decreased after administration of TEA or 4-AP (P<0.05);Compared to ad-ministration of TEA or 4-AP,the current amplitude in BASMCs of the two kind rats was significantly in-creased after administration of TEA+RMF or 4-AP+RMF (P<0.05).Conclusion Bkcaand Kv currents in both BASMCs of SHR and WKY rats were activated by RMF in a voltage-dependent and dose-dependent manner,and the effect of RMF on BKCaand Kvactivition currents in BASMCs of SHR was weaker than WKY rats.