Effect of Acidosis on Contractile Function in the Newborn Rabbit Heart
Effect of Acidosis on Contractile Function in the Newborn Rabbit Heart
复制标题
酸中毒对新生兔心脏收缩功能的影响
DOI：
10.1203/00006450-198505000-00015
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发表时间：
1985
影响因子：
3.6
通讯作者：
A. Takao
中科院分区：
文献类型：
--
作者：
T. Nakanishi;H. Okuda;M. Nakazawa;A. Takao
摘要：在新生兔和成年兔中研究了呼吸性和代谢性酸中毒（pH约6.8）对心肌功能的影响。在离体动脉灌注心脏标本上研究了心脏的力学功能。酸中毒是通过增加灌注液二氧化碳分压或减少碳酸氢盐含量引起的。在呼吸性酸中毒过程中，成人的发展性张力（DT）下降至对照组的43 ± 3%（n = 18），这种下降明显大于新生儿（DT = 92 ± 4%，n = 6）。呼吸性酸中毒对DT的抑制作用甚至在高细胞外Ca时也能观察到。在代谢性酸中毒过程中，机械功能逐渐下降，成人在进入酸中毒30 min时DT为对照组的78 ± 3%（n = 6）。成年人的DT抑制显著大于新生儿（30分钟时的DT =对照组的96 ± 1%，n = 6）。配对t检验统计分析显示，呼吸性酸中毒，而不是代谢性酸中毒，引起显着的负性肌力的新生儿。分离肌原纤维，并在10−8至10−4 M Ca和pH 7.1（对照）、6.5和6.0下测量ATP酶。在新生儿和成人中，降低pH同样抑制ATP酶活性。通过用HCl滴定肌肉匀浆来测定细胞内缓冲能力。虽然初始pH值没有不同，但向匀浆中加入HCl导致新生儿pH值降低较少。这些数据表明，新生儿心脏的收缩功能对酸中毒更具抵抗力，这可能部分是由于细胞内缓冲能力更大。
ABSTRACT: Effects of respiratory and metabolic acidosis (pH approximately 6.8) on myocardial function were studied in the newborn and adult rabbits. Mechanical function was studied in the isolated arterially perfused heart preparation. Acidosis was induced either by increase of the perfusate Pco2 or by decrease of the bicarbonate content. During respiratory acidosis, developed tension (DT) decreased to 43 ± 3% of control (n = 18) in the adult and this depression was significantly greater than in the newborn (DT = 92 ± 4%, n = 6). Depression of DT by respiratory acidosis was observed even at high extracellular Ca. During metabolic acidosis, mechanical function decreased gradually and DT at 30 min into acidosis in the adult was 78 ± 3% of control (n = 6). This depression of DT in the adult was significantly greater than in the newborn (DT at 30 min = 96 ± 1% of control, n = 6). Statistical analysis using paired t test showed that respiratory acidosis, but not metabolic acidosis, caused significant negative inotropism in the newborn. Myofibrils were isolated and the ATPase was measured at 10−8 to 10−4 M Ca and at pH of 7.1 (control), 6.5, and 6.0. Reducing pH depressed the ATPase activity similarly in the newborn and adult. Intracellular buffer capacity was determined by titrating muscle homogenate with HC1. Although the initial pH was not different, addition of HCI to the homogenate caused less decrease in pH in the newborn. These data indicate that contractile function in the newborn heart is more resistant to acidosis and this may be due partly to the greater intracellular buffer capacity.
心肌细胞内钙浓度的测量：正性肌力干预和缺氧的影响。
影响因子：
5
作者：
Allen,DG;Orchard,CH
通讯作者：
Orchard,CH