Intracellular pH and cell-to-cell transmission in sheep Purkinje fibers.
Intracellular pH and cell-to-cell transmission in sheep Purkinje fibers.
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绵羊浦肯野纤维的细胞内 pH 值和细胞间传输。
DOI：
10.1016/s0006-3495(89)82780-8
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发表时间：
1989
影响因子：
3.4
通讯作者：
Pressler,ML
中科院分区：
文献类型：
--
作者：
Pressler,ML
在一些组织中，细胞内pH值（pHi）是细胞间通讯的重要修饰因子，但其在心脏组织中的作用尚不确定。本研究考察了胞质质子对心脏浦肯野纤维电张力扩散和传导速度的影响。电缆分析提供了内部纵向电阻（ri）的值，ph选择微电极监测CO2和HCO3-变化期间的pHi。在恒定的[HCO3-] CO2变化过程中，静息纤维的ri变化与细胞内自由质子浓度（[H+]i）成正比。然而，在pHi 6.9-7.8之间，对ri的影响较小，并且预测[H+]i每增加10 nM， ri仅增加2.2%。其他研究结果表明，胞质质子的滴定可能不会直接产生ri的变化：(a)对于[H+]i的相同变化，如果在CO2变化过程中丢失碳酸氢盐，则对ri的影响约为三倍（[H+]i每增加10 nM增加6.8%）。(b)在连续扰动中，ph相关的ri变化之前有一个时间延迟（1-5分钟），在[H+]i-ri关系中产生滞后。(c)同样的CO2变化在起搏时对ri的方向和幅度的改变与静止时不同。累积的结果表明，质子对心脏中ri的作用可能服从于另一种调节剂或由另一种ph依赖性物质或反应介导。
Intracellular pH (pHi) is a significant modifier of cell-to-cell communication in some tissues but its role is uncertain in heart tissue. The present studies examined the effect of cytosolic protons on electrotonic spread and conduction velocity in cardiac Purkinje fibers. Cable analysis provided values for internal longitudinal resistance (ri) and pH-selective microelectrodes monitored pHi during CO2 and HCO3- alterations. Resting fibers developed changes in ri that were proportional to intracellular free proton concentration ([H+]i) during CO2 changes at constant [HCO3-]. However, the effects on ri were small between pHi 6.9–7.8 and predicted only a 2.2% increase in ri per 10 nM increase in [H+]i. Other findings suggested that titration of cytosolic protons may not directly produce the changes in ri: (a) For an equal change in [H+]i, the effects on ri were roughly three times greater (6.8% increase per 10 nM rise in [H+]i) if bicarbonate was lost during CO2 changes. (b) pH-associated changes in ri were preceded by a time delay (1–5 min) producing hysteresis in the [H+]i-ri relation during successive perturbations. (c) The same CO2 variations modified the direction and magnitude of ri differently during pacing than at rest. The cumulative results suggest that the action of protons on ri in the heart may be subordinate to another regulator or mediated by another pH-dependent substance or reaction.