Robertson S P, Kerrick W G
Pflugers Arch. 1979 May 15;380(1):41-5. doi: 10.1007/BF00582610.
Ca2+-activated isometric force was recorded is skinned (sarcolemma mechanically removed) segments of frog skeletal muscle fibers immersed in bathing solution of different pH (5.0--10.5) and Ca2+ concentrations. Force in maximally activated fibers was near zero at pH 5.5, increased as pH increased to 7.5, remained relatively constant until pH 9.0 and then rapidly declined to zero by pH 10.5. The Ca2+ concentration at which 50% of maximum force was developed decreased 25-fold as pH increased from 5.5--7.5. The data also indicate that, while the fibers remains viable with acidosis, they deteriorate rapidly with alkalosis. These observations may be relevant clinically, since they parallel known effects of acidosis on cardiac contractility. The possible sites of action of H+ on the Ca2+-activated force generating mechanisms are discussed.
在不同pH值（5.0 - 10.5）和钙离子浓度的浴液中，对剥除肌膜（机械去除肌膜）的青蛙骨骼肌纤维段记录钙离子激活的等长力。在pH 5.5时，最大激活纤维中的力接近零，随着pH值升至7.5而增加，直至pH 9.0保持相对恒定，然后在pH 10.5时迅速降至零。当pH值从5.5升至7.5时，产生最大力的50%时的钙离子浓度降低了25倍。数据还表明，虽然纤维在酸中毒时仍能存活，但在碱中毒时会迅速恶化。这些观察结果可能具有临床相关性，因为它们与酸中毒对心脏收缩性的已知影响相似。讨论了氢离子对钙离子激活的力产生机制的可能作用位点。
