双苯氟嗪对豚鼠心室肌细胞L-钙电流的影响

目的:观察双苯氟嗪(Dip)对豚鼠心室肌细胞L-型钙电流(I_(Ca-L))的影响。方法:酶解法制备单个心室肌细胞。应用全细胞膜片箝技术记录豚鼠单个心室肌细胞钙电流。结果:在0.3-30μmol/L范围内,Dip可浓度依赖性地降低电压依赖性激活I_(Ca-L)峰值,被Dip 3μmol/L所抑制的I_(Ca-L)在冲洗5min后可得到部份恢复。但Dip对I_(Ca-L)的电压依赖特征,最大激活电压,以及I_(Ca-L)稳态激活无明显影响。在Dip3μmol/L存在下,半数激活电压(V_(0.5))和斜率参数(к)与对照组相比,差异均无显著性。V_(0.5)分别为(-12.8±1.7)mV和(-13.2±2.4)mV,к分别为(7.1±0.4)mV和(7.5±0.5)mV(P>0.05)。Dip3μmol/L可明显使钙电流稳态失活曲线左移,加速钙通道电压依赖性稳态失活。V_(0.5)分别为(-19.7±2.4)mV和(-31±6)mV,к分别为(3.6±0.3)mV和(1.8±0.2)mV(P<0.05).Dip 3μmol/L还使I_(Ca-L)从失活状态下的恢复明显减慢。结论:Dip主要作用于L-型钙通道的失活状态,加速钙通道失活,并使其从失活状态下恢复减慢,从而抑制I_(Ca-L)。

Effect of dipfluzine on L-type calcium current in guinea pig ventricular myocytes

AIM: To study the effect of dipfluzine (Dip) on L-type calcium current in guinea pig ventricular myocytes. METHODS: Single myocytes were dissociated by enzymatic dissociation method. The current was recorded with the whole-cell configuration of the patch-clamp technique. RESULTS: Dip (0.3 - 30 micromol/L) reduced the voltage-dependently activated peak value of I(Ca-L) in a concentration-dependent manner. The characteristics of I-V relationship were not greatly altered by Dip, and the maximal activation voltage of I(Ca-L) in the presence of Dip was not different from that of control. Steady-state activation of I(Ca-L) was not affected markedly, and the half activation potential V(0.5)) and the slope factor (kappa) in the presence of Dip 3 micromol/L were not markedly different from those of the control. V(0.5) value was (-12.8 +/- 1.7) mV in the control and (-13.2 +/- 2.4) mV in the presence of Dip 3 micromol/L. The kappa value was (7.1 +/- 0.4) mV in the control and (7.5 +/- 0.5) mV in the presence of Dip 3 micromol/L (n = 7 cells from 3 hearts, P > 0.05). Dip 3 micromol/L markedly shifted the steady-state inactivation curve of I(Ca-L) to the left, and accelerated the voltage-dependent steady-state inactivation of calcium current. V(0.5) value was (-19.7 +/- 2.4) mV in the control and (-31 +/- 6) mV in the presence of Dip 3 micromol/L. The kappa value was (3.6 +/- 0.3) mV in the control and (1.8 +/- 0.2) mV in the presence of Dip 3 micromol/L (n = 4 cells from 2 hearts, P < 0.05). Dip 3 micromol/L markedly delayed half-recovery time of Ca2+ channel from inactivation from (40 +/- 11) to (288 +/- 63) ms (n = 4, P < 0.01). CONCLUSION: Dip mainly acts on the inactivated state of L-type calcium channel, accelerates the inactivation of calcium channel, and slows the recovery of calcium channel from inactivated state in guinea pig ventricular myocytes, through which the I(Ca-L) is inhibited.