Yabek S M, Kato R, Singh B N
Pediatr Res. 1985 Dec;19(12):1263-7. doi: 10.1203/00006450-198512000-00008.
Standard microelectrode techniques were utilized to evaluate the effects of acute hypoxia on the cellular electrical activity of neonatal and adult ventricular myocardium. Control action potential parameters from adult and neonatal tissues were not significantly different. Thirty minutes of acute hypoxic superfusion significantly (p less than 0.05) reduced all adult action potential indices. In neonatal preparations, only action potential duration at 50% repolarization (-17%) and action potential duration at 90% repolarization (-12%) were reduced significantly. After 60 min of hypoxia, action potential amplitude, maximum diastolic potential, and phase 0 upstroke velocity from neonates were still not reduced significantly. The alteration in neonatal action potential parameters induced by 1 h of hypoxic superfusion (5.5 mM glucose) were all reversed by 16.5 mM glucose despite continued hypoxia. Exclusion of glucose from the hypoxic superfusate did not greatly affect the response of neonatal tissues to hypoxia. In adult action potentials, the degree of decrease for each action potential parameter was markedly greater compared to the hypoxic solution with normal (5.5 mM) glucose. Following hypoxic superfusion of neonatal preparations with 0 mM glucose, reoxygenation with 16.5 mM glucose resulted in action potential parameters with exceeded control values by 4 to 25%. Our data indicate a greater resistance of developing myocardium to the detrimental effects of hypoxia on cellular electrical activity. This seems to be related to a greater glycolytic activity of neonatal myocardium compared to adult hearts.
采用标准微电极技术评估急性缺氧对新生和成年心室心肌细胞电活动的影响。成年和新生组织的对照动作电位参数无显著差异。30分钟的急性缺氧灌注显著（p<0.05）降低了所有成年动作电位指标。在新生组织标本中，只有复极化50%时的动作电位时程（-17%）和复极化90%时的动作电位时程（-12%）显著降低。缺氧60分钟后，新生动物的动作电位幅度、最大舒张电位和0期去极化速度仍未显著降低。尽管持续缺氧，但16.5 mM葡萄糖可逆转1小时缺氧灌注（5.5 mM葡萄糖）诱导的新生动物动作电位参数改变。缺氧灌注液中不含葡萄糖对新生组织对缺氧的反应影响不大。在成年动作电位中，与含正常（5.5 mM）葡萄糖的缺氧溶液相比，每个动作电位参数的降低程度明显更大。新生组织标本用0 mM葡萄糖进行缺氧灌注后，再用16.5 mM葡萄糖复氧，导致动作电位参数超过对照值4%至25%。我们的数据表明，发育中的心肌对缺氧对细胞电活动的有害影响具有更大的抵抗力。这似乎与新生心肌比成年心脏具有更高的糖酵解活性有关。
