Crichton C A, Templeton A G, Smith G L
Institute of Physiology, Glasgow University, United Kingdom.
Cardiovasc Res. 1994 Sep;28(9):1378-84. doi: 10.1093/cvr/28.9.1378.
The aim was to investigate the effect of altered bathing pH on calcium activated force generated by the contractile proteins in an alpha toxin permeabilised phasic (rat portal vein) and tonic (human umbilical artery) smooth muscle.
Strips of the two muscles were permeabilised using crude alpha toxin from Staphylococcus aureus (2 mg.ml-1). The relationship between [Ca2+] and tension was then examined at different bathing pH values. [Ca2+] was monitored using indo-1 fluorescence.
GTP-gamma-S (100 microM) potentiated maximum calcium activated force in rat portal vein on average to 146%, but had no significant effect on human umbilical artery, confirming the difference in contractile behaviour between the two muscles. Lowering bathing pH from 7.2 to 6.7 depressed submaximal calcium activated force and increased maximum calcium activated force in rat portal vein. Raising bathing pH from 7.2 to 7.7 depressed both submaximal and maximum calcium activated force in rat portal vein. Altered bathing pH had no significant effect on either maximum or submaximal calcium activated force in human umbilical artery. The calcium sensitivity of tension production was not significantly effected by acidic pH in either preparation. However, alkaline pH caused a similar fall in the calcium sensitivity in both preparations.
Tension generated from the contractile proteins of a phasic smooth muscle (rat portal vein) are more sensitive to altered bathing pH than those of a tonic smooth muscle (human umbilical artery).
研究改变灌流液pH值对α毒素通透的时相性（大鼠门静脉）和紧张性（人脐动脉）平滑肌收缩蛋白产生的钙激活力的影响。
用金黄色葡萄球菌粗制α毒素（2mg/ml）使两种肌肉的肌条通透。然后在不同的灌流液pH值下检测[Ca2+]与张力之间的关系。使用indo-1荧光监测[Ca2+]。
GTP-γ-S（100μM）使大鼠门静脉的最大钙激活力平均增强至146%，但对人脐动脉无显著影响，证实了两种肌肉收缩行为的差异。将灌流液pH值从7.2降至6.7会降低大鼠门静脉次最大钙激活力并增加最大钙激活力。将灌流液pH值从7.2升至7.7会降低大鼠门静脉次最大和最大钙激活力。改变灌流液pH值对人脐动脉的最大或次最大钙激活力均无显著影响。两种制剂中，酸性pH对张力产生的钙敏感性均无显著影响。然而，碱性pH在两种制剂中均导致钙敏感性类似下降。
时相性平滑肌（大鼠门静脉）收缩蛋白产生的张力比紧张性平滑肌（人脐动脉）对改变灌流液pH值更敏感。
