Gating of mammalian cardiac gap junction channels by transjunctional voltage.
Gating of mammalian cardiac gap junction channels by transjunctional voltage.
复制标题
通过跨接点电压对哺乳动物心脏间隙连接通道进行门控。
DOI：
10.1016/s0006-3495(92)81573-4
复制
发表时间：
1992
影响因子：
3.4
通讯作者：
Veenstra,RD
中科院分区：
文献类型：
--
作者：
Wang,HZ;Li,J;Lemanski,LF;Veenstra,RD
大量的双细胞电压钳研究已经得出结论，哺乳动物心脏间隙连接的电导不受跨接电压（Vj）曲线的调节，尽管据报道新生大鼠心室肌细胞的低电导对之间的间隙连接通道表现出Vj依赖性行为。本研究采用双全细胞膜片钳技术，定量研究了成对的3-d新生仓鼠心室肌细胞宏观缝隙连接电导（gj）对跨接电压的依赖性。免疫定位与位点特异性抗血清直接对大鼠连接蛋白43，43 kD的间隙连接蛋白，从其cDNA序列预测的氨基酸252-271，特异性染色区培养的心肌细胞之间的接触。新生仓鼠肌细胞对的瞬时电流-电压（Ij-Vj）关系在检查的整个电压范围内呈线性（0小于或等于Vj小于或等于+/- 100 mV）。然而，当Vj大于+/- 50 mV时，稳态Ij-Vj关系为非线性。失活和恢复过程均遵循单指数时间过程（tau失活=100- 1，000 ms，tau恢复约等于300 ms）。然而，Ij在极性反转后迅速恢复。标准化稳态结电导-电压关系（Gss-Vj）为钟形曲线，可通过双态Boltzmann方程充分描述，最小Gj为0.32-0.34，半失活电压为-69和+61 mV，有效化合价为2.4-2.8。间隙连接通道电流（ij）的记录产生线性ij-Vj关系，斜率电导约为20-30和45-50 pS。基于玻尔兹曼关系和极性反转数据的动力学模型表明，打开（α）和关闭（β）速率常数具有几乎相同的电压灵敏度，Vo为+/- 62 mV。在这项研究中提出的数据是不一致的应急门控方案（两个相同的门串联）提出的其他更多的Vj依赖性间隙连接，或者建议，每个门响应于所施加的Vj独立的状态（打开或关闭）的其他门。
Numerous two-cell voltage-clamp studies have concluded that the electrical conductance of mammalian cardiac gap junctions is not modulated by the transjunctional voltage (Vj) profile, although gap junction channels between low conductance pairs of neonatal rat ventricular myocytes are reported to exhibit Vj-dependent behavior. In this study, the dependence of macroscopic gap junctional conductance (gj) on transjunctional voltage was quantitatively examined in paired 3-d neonatal hamster ventricular myocytes using the double whole-cell patch-clamp technique. Immunolocalization with a site-specific antiserum directed against amino acids 252–271 of rat connexin43, a 43-kD gap junction protein as predicted from its cDNA sequence, specifically stained zones of contact between cultured myocytes. Instantaneous current-voltage (Ij-Vj) relationships of neonatal hamster myocyte pairs were linear over the entire voltage range examined (0 less than or equal to Vj less than or equal to +/- 100 mV). However, the steady-state Ij-Vj relationship was nonlinear for Vj greater than +/- 50 mV. Both inactivation and recovery processes followed single exponential time courses (tau inactivation=100–1,000 ms, tau recovery approximately equal to 300 ms). However, Ij recovered rapidly upon polarity reversal. The normalized steady-state junctional conductance-voltage relationship (Gss-Vj) was a bell-shaped curve that could be adequately described by a two-state Boltzmann equation with a minimum Gj of 0.32–0.34, a half-inactivation voltage of -69 and +61 mV and an effective valence of 2.4–2.8. Recordings of gap junction channel currents (ij) yielded linear ij-Vj relationships with slope conductances of approximately 20–30 and 45–50 pS. A kinetic model, based on the Boltzmann relationship and the polarity reversal data, suggests that the opening (alpha) and closing (beta) rate constants have nearly identical voltage sensitivities with a Vo of +/- 62 mV. The data presented in this study are not consistent with the contingent gating scheme (for two identical gates in series) proposed for other more Vj-dependent gap junctions and alternatively suggest that each gate responds to the applied Vj independently of the state (open or closed) of the other gate.