Adams G R, Fisher M J, Meyer R A
Department of Physiology, Michigan State University, East Lansing 48824.
Am J Physiol. 1991 Apr;260(4 Pt 1):C805-12. doi: 10.1152/ajpcell.1991.260.4.C805.
Peak tetanic tension was measured during acidosis resulting from either hypercapnia or repetitive tetanic stimulation in isolated, arterially perfused cat biceps brachii (predominantly fast twitch) or soleus (slow twitch) muscles. Phosphocreatine (PCr), Pi, intracellular pH (pHi), and extracellular pH (pHo) were monitored by 31P-nuclear magnetic resonance spectroscopy. During repetitive stimulation under normocapnic conditions (5% CO2, pHo 7.4) Pi increased, pHi decreased from 7.1 to 6.3, and there were significant correlations between both pHi and calculated [H2PO4-] vs. peak tetanic force in both muscle types. However, hypercapnic perfusion (70% CO2, pHo, 6.7, pHi 6.4-6.5) had no effect on peak tetanic force, and there was no significant correlation between pHi or [H2PO4-] during hypercapnia in either muscle. The results indicate that decreased peak tetanic force during repetitive stimulation is not directly due to changes in pHi or diprotonated phosphate.
在由高碳酸血症或重复强直刺激导致的酸中毒期间，对分离的、经动脉灌注的猫肱二头肌（主要是快肌纤维）或比目鱼肌（慢肌纤维）测量强直收缩峰值张力。通过磷-31核磁共振波谱监测磷酸肌酸（PCr）、无机磷（Pi）、细胞内pH值（pHi）和细胞外pH值（pHo）。在正常碳酸血症条件下（5%二氧化碳，pHo 7.4）进行重复刺激时，Pi增加，pHi从7.1降至6.3，并且在两种肌肉类型中，pHi和计算出的[H2PO4-]与强直收缩峰值力之间均存在显著相关性。然而，高碳酸血症灌注（70%二氧化碳，pHo 6.7，pHi 6.4 - 6.5）对强直收缩峰值力没有影响，并且在高碳酸血症期间，两种肌肉中的pHi或[H2PO4-]之间均无显著相关性。结果表明，重复刺激期间强直收缩峰值力降低并非直接由于pHi或双质子化磷酸盐的变化。
