Cechetto D, Mainwood G W
Pflugers Arch. 1978 Sep 29;376(3):251-8. doi: 10.1007/BF00584959.
A method for measuring the net acid base exchange in an isolated rat diaphragm preparation is described. Particular attention is paid to monitoring the functional status and maintaining optimal diffusion conditions. A steady net acid efflux of the order of 250 n mole/g-min is found in the resting state. This increases following a series of isometric contractions. In the resting state the total measured lactate + pyruvate efflux was found to be less than the net acid efflux. The net acid efflux increases following a sudden decrease in pCO2 and decreases or reverses following a sudden increase in pCO2 or a decrease in external bicarbonate. The net base loss during a period of 1 h following the exposure to high (20%) CO2 represents a large fraction of the predicted total bicarbonate generated within the fibres by non-bicarbonate buffers. This indicates that the effects of intracellular non-bicarbonate buffers can be transmitted to the external solution following a change in pCO2. The most plausible explanation is that passive bicarbonate ion movements are responsible. Values of the 'apparent PHCO3' have been calculated and vary under different conditions from a value of 1.3 X 10(-7) to 1.9 X 10(-6) cm-s-1.
本文描述了一种测量离体大鼠膈肌制剂中净酸碱交换的方法。特别关注监测功能状态并维持最佳扩散条件。在静息状态下发现稳定的净酸流出量约为250 nmol/g·min。在一系列等长收缩后，该值会增加。在静息状态下，测得的乳酸 + 丙酮酸总流出量低于净酸流出量。pCO2突然降低后净酸流出量增加，pCO2突然升高或外部碳酸氢盐减少后净酸流出量减少或逆转。暴露于高（20%）CO2后1小时内的净碱损失占非碳酸氢盐缓冲剂在纤维内产生的预测总碳酸氢盐的很大一部分。这表明pCO2变化后细胞内非碳酸氢盐缓冲剂的作用可以传递到外部溶液中。最合理的解释是被动碳酸氢根离子运动起作用。已计算出“表观PHCO3”值，在不同条件下其值从1.3×10(-7)到1.9×10(-6) cm·s-1不等。
