瑞芬太尼对正常和高血压大鼠基底动脉平滑肌细胞的不同作用

Different effects of remifentanil on basilar artery smooth muscle cells of normotensive and hypertensive rats

目的评价瑞芬太尼对正常和高血压大鼠基底动脉平滑肌细胞上大电导钙激活钾通道(BKCa)和电压门控钾通道(Kv)激活电流的影响。方法自发性高血压大鼠(spontaneously hypertensive rats,SHR)和同源正常血压(wistar-kyoto,WKY)大鼠,采用酶消化法急性分离基底动脉平滑肌细胞,每种大鼠选择6个基底动脉平滑肌细胞,采用全细胞膜片钳技术记录外向电流幅度。加入瑞芬太尼3×10-7mol/L,分别记录所设置的方波刺激(step刺激)方案中所有刺激电压下给药前(基础水平)和给药后电流幅度,并计算净电流=给药后电流幅度-基础值;采用浓度累积法给药,分别记录+60 m V刺激电压下给药前(基础值)和给予10-10、10-9、10-8、10-7、10-6、10-5mol/L瑞芬太尼后电流幅度,计算电流增加率和瑞芬太尼增加基底动脉平滑肌细胞电流幅度的半数有效浓度(EC50);另取每种大鼠6个基底动脉平滑肌细胞,加入瑞芬太尼3×10-7mol/L后分别给予BKCa阻滞剂四乙胺(tetraethylammonium,TEA)和Kv阻滞剂4-氨基吡啶(4-aminopyridine,4-AP),再分别加入其相应的瑞芬太尼混合液,记录每一次给药后的电流幅度。结果两种大鼠基底动脉平滑肌细胞给瑞芬太尼后在0、+20、+40和+60 m V刺激电压下产生的净电流依次明显增大(P<0.05);10-10、10-9、10-8、10-7mol/L瑞芬太尼作用下,两种大鼠基底动脉平滑肌细胞外向电流增加率依次明显升高(P<0.05);与WKY大鼠比较,瑞芬太尼增加SHR基底动脉平滑肌细胞电流幅度的(EC50)明显升高(P<0.05);与基础值比较,两种大鼠基底动脉平滑肌细胞瑞芬太尼给药后电流幅度明显升高,TEA给药后或4-AP给药后电流幅度明显降低(P<0.05);与TEA给药后或4-AP给药后比较,TEA+瑞芬太尼给药后或4-AP+瑞芬太尼给药后两种大鼠基底动脉平滑肌细胞电流幅度明显升高(P<0.05)。结论瑞芬太尼呈电压依赖性和浓度依赖性激活两种大鼠基底动脉平滑肌细胞BKCa和Kv电流,瑞芬太尼对SHR基底动脉平滑肌细胞上BKCa和Kv激活电流的作用较WKY大鼠弱。

Objective To evaluate the effects of remifentanil （RMF） on large conductance calcium-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 amplitude 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 （3×10-7 mol/L） were recorded respectively and net current was calculated （net current=current 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, 10-5 mol/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 （3×10-7 mol/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, 10-7 RMF successively and significantly went upward （P〈0.05）. Compared to WKY rats, the half-effective concentration （EC50） of RMF increasing the current amplitude in BASMCs of SHR significantly rose （P〈0.05）. Compared with the baseline, the current amplitude in BASMCs of the two kind rats was significantly increased after administration of RMF, and decreased after administration of TEA or 4-AP （P〈0.05）; Compared to administration of TEA or 4-AP, the current amplitude in BASMCs of the two kind rats was significantly increased after administration of TEA＋RMF or 4-AP＋RMF （P〈0.05）. Conclusion BKca and 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 KV activition currents in BASMCs of SHR was weaker than WKY rats.