低Ca^(2+)对豚鼠心室乳头肌电缆特性的影响

INFLUENCES OF LOW Ca^(2+) ON THE CABLE PROPERTIES OF GUINEA PIG PAPILLARY MUSCLE

应用常规细胞内微电极技术和一支细胞外玻璃吸引电极,观察低Ca^(2+)对豚鼠心室乳头肌电缆特性及动作电位传导速度的影响。实验结果表明,1/6正常Ca^(2+)浓度(0.3mmol/L)溶液灌流时,与正常对照相比,空间常数减小23.9％(p<0.01),细胞内纵向电阻增大37.1％(p<0.01),动作电位传导速度减小16.1％(p<0.01)。单纯缺氧时,与正常对照相比,空间常数减小29.4％(p<0.01),膜时间常数减小30.1％(p<0.01),细胞内纵向电阻增大100％(p<0.01),动作电位传导速度减小28％(p<0.01)。低Ca^(2+)(0.6mmol/L)加缺氧时,上述变化更加明显,与正常对照相比,空间常数减小39.4％(p<0.01),膜时间常数减小25.8％(p<0.05),细胞内纵向电阻增大140.9％(p<0.01),动作电位传导速度减小37.7％(p<0.01)。

By using technique of the conventional intracellular microelectrode and an extracellular glass suction electrode, the influences of low Ca2+ on the cable property and the conduction velocity of guinea pig papillary muscle were examined. When the preparation was superfused with Tyrode's solution containing 1/6 of normal Ca2+ concentration (0.3mmol/L), the space constant and conduction velocity were reduced by 23.9%(p<0.01) and 16.1% (p<0.01) respectively as compared with the control, while internal longitudinal resistance was enhanced by 37. l%(p<0.01). Changes occurred during exposure to hypoxia were decreases in space constant, time constant of membrane and conduction velocity by 29.4%, 30.1% and 28%(p<0.01) respectively and increase in internal longitudinal resistance by 100% (p< 0.01) as compared with the control. More obvious changes were observed when the preparation was exposed to hypoxia in 0.6mmol/L Ca2+ Tyrode's solution. As compared with the control, space constant, time constant of membrane and conduction velocity were reduced by 39.4% (p<0.01), 25.8% (p<0.05) and 37.7% (p<0.01) respectively, while internal longitudinal resistance was enhanced by 140.9%(p<0.01).