Allard Y E
Department of Physiology, University of Ottawa, Ont., Canada.
Can J Physiol Pharmacol. 1988 Dec;66(12):1560-4. doi: 10.1139/y88-255.
Intracellular pH (pHi), measured with H+-selective microelectrodes, in quiescent frog sartorius muscle fibres was 7.29 +/- 0.09 (n = 13). Frog muscle fibres were superfused with a modified Ringer solution containing 30 mM HEPES buffer, at extracellular pH (pHo) 7.35. Intracellular pH decreased to 6.45 +/- 0.14 (n = 13) following replacement of 30 mM NaCl with sodium lactate (30 mM MES, pHo 6.20). Intracellular pH recovery, upon removal of external lactic acid, depended on the buffer concentration of the modified Ringer solution. The measured values of the pHi recovery rates was 0.06 +/- 0.01 delta pHi/min (n = 5) in 3 mM HEPES and was 0.18 +/- 0.06 delta pHi/min (n = 13) in 30 mM HEPES, pHo 7.35. The Na+-H+ exchange inhibitor amiloride (2 mM) slightly reduced pHi recovery rate. The results indicate that the net proton efflux from lactic acidotic frog skeletal muscle is mainly by lactic acid efflux and is limited by the transmembrane pH gradient which, in turn, depends on the extracellular buffer capacity in the diffusion limited space around the muscle fibres.
用氢离子选择性微电极测量，在静息的青蛙缝匠肌纤维中，细胞内pH值（pHi）为7.29±0.09（n = 13）。青蛙肌肉纤维用含有30 mM HEPES缓冲液的改良林格氏溶液进行灌流，细胞外pH值（pHo）为7.35。用乳酸钠（30 mM MES，pHo 6.20）取代30 mM氯化钠后，细胞内pH值降至6.45±0.14（n = 13）。去除外部乳酸后，细胞内pH值的恢复取决于改良林格氏溶液的缓冲浓度。在3 mM HEPES中，pHi恢复率的测量值为0.06±0.01 ΔpHi/分钟（n = 5），在30 mM HEPES（pHo 7.35）中为0.18±0.06 ΔpHi/分钟（n = 13）。钠离子-氢离子交换抑制剂氨氯吡脒（2 mM）略微降低了pHi恢复率。结果表明，乳酸酸中毒青蛙骨骼肌的净质子外流主要通过乳酸外流，并且受到跨膜pH梯度的限制，而跨膜pH梯度又取决于肌肉纤维周围扩散受限空间中的细胞外缓冲能力。
