Developmental changes of action potential configuration and I(to) in canine epicardium.
Developmental changes of action potential configuration and I(to) in canine epicardium.
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犬心外膜动作电位构型和 I(to) 的发育变化。
DOI：
10.1152/ajpheart.1995.268.6.h2513
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
GilmourJr,RF
中科院分区：
文献类型：
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作者：
Pacioretty,LM;GilmourJr,RF
在犬胎龄至60周龄的心外膜上测定了瞬时外向电流（I（to））和动作电位构型的发育变化。通过分别测量动作电位1相的振幅和动作电位时程来估计I（to）对快速初始复极和终末复极的贡献。从胎儿到40周，1相振幅逐渐下降，此后保持不变。动作电位时程从胎龄至2周下降，至20周增加，此后趋于下降。+40 mV处的峰值I（to）从2至60周逐渐增加。但2-10周的I（to）密度低于20-60周。衰减的时间常数的I（到）随年龄增加，从2至60周，而稳态电压依赖性的失活不随年龄而变化。从失活恢复的初始快速阶段的时间常数从2周下降到10周，此后保持不变。较缓慢发展阶段的时间常数不随年龄而变化。年龄依赖性的减少相1振幅不一定符合显着增加I（到）密度表明，成熟的其他离子电流或运输机制可能有助于发展改变相1复极。
Developmental changes of the transient outward current (I(to)) and action potential configuration were determined in canine epicardium ranging in age from fetal to 60 wk. The contributions of I(to) to rapid initial repolarization and to terminal repolarization were estimated by measuring the amplitude of phase 1 of the action potential and action potential duration, respectively. Phase 1 amplitude decreased progressively from fetal to 40 wk and remained constant thereafter. Action potential duration decreased from fetal to 2 wk, increased to 20 wk, and tended to decrease thereafter. Peak I(to) at +40 mV increased progressively from 2 to 60 wk. However, I(to) density was less at 2-10 wk than at 20-60 wk. The time constant of decay of I(to) increased with age from 2 to 60 wk, whereas the steady-state voltage dependence of inactivation did not vary with age. The time constant for the initial rapid phase of recovery from inactivation decreased from 2 to 10 wk and remained constant thereafter. The time constant for the more slowly evolving phase did not vary with age. The observation that the age-dependent reduction in phase 1 amplitude did not necessarily coincide with significant increases in I(to) density suggests that maturation of other ionic currents or transport mechanisms may contribute to developmental alterations of phase 1 repolarization.