豚鼠冠状动脉微动脉细胞静息膜电位的分布特性及机制

The distribution and mechanism of coronary arteriole cell resting membrane potential in guinea pigs

目的:观察冠状动脉微动脉细胞静息膜电位(RP)的分布特性及形成机制。方法:离体豚鼠冠状动脉微动脉(直径小于100μm)上,应用细胞内微电极技术记录细胞RP。结果:①成功记录到112个细胞,细胞平均RP为(-65±4.2)mV,应用高斯函数拟合后细胞RP呈双峰状分布,两个峰值分别为-43和-74 mV,分别称为高和低RP。10mmol/L K+和3μmol/L乙酰胆碱(ACh)在高RP细胞上引起超极化反应,幅度分别为(-7.4±0.87)mV(n=13)和(-15±1.2)mV(n=16)。而在低RP细胞上引起去极化反应,反应幅度分别为(9.6±1.2)mV(n=23)和(8.7±0.69)mV(n=15)。②低RP细胞上内向整流K+通道(Kir)阻断剂Ba2+引起浓度依赖的去极化,EC50为120μmol/L。应用≥100μmol/L Ba2+后低RP细胞转变为高RP,高K+和ACh介导的反应形式也发生相应改变。结论:冠状动脉微动脉细胞RP呈双峰分布,高K+和ACh在不同RP水平反应形式不同,这种独特的RP分布通过激活或失活Kir介导。

Objective：To investigate the distribution and mechanism of coronary arteriole（CA） cell resting membrane potential（RP） in guinea pigs.Methods：Cell RP was recorded by intracellular microelectrode in isolated guinea pig coronary arteriole（diameter 100 μm）.Results：①Experiments were carried out in 112 cells with a mean RP of（-65±4.2）mV,the distribution of coronary arteriole cell RP fitted by Gaussian function was bimodal,one peak was-43 mV termed high RP,the other was-74 mV termed low RP.10 mmol/L K＋ and 3 μmol/L acetylcholine（ACh） induced hyperpolarization in high-RP cells with（7.4±0.87）mV（n=13） and（-15±1.24）mV（n=16） respectively,and induced depolarization in low-RP cells with（9.6±1.2）mV（n=23） and（8.7±0.69）mV（n=15） respectively.②The inward rectifier K＋ channel（Kir） blocker Ba2＋ caused concentration-dependent depolarization in low-RP cells with an EC50 of 120 μmol/L 100 μmol/L Ba2＋or higher could shift low-RP cells to high-RP state,the response of these cells to high K＋ and ACh became a hyperpolarization.Conclusion：The distribution of coronary vascular cell RP is bimodal,high K＋ and ACh induce different responses in low and high RP cells.The two RP states are exchangeable mainly due to all-or-none conductance changes of Kir.