Connett R J
Department of Physiology, School of Medicine and Dentistry, University of Rochester, New York 14642.
J Appl Physiol (1985). 1987 Dec;63(6):2360-5. doi: 10.1152/jappl.1987.63.6.2360.
Muscles sampled from a vascularly isolated autoperfused dog gracilis by fast freezing techniques at 5, 10, 15, 30, 60, and 180 s after the initiation of twitch contractions at 4 Hz were analyzed for phosphocreatine, creatine, ATP, lactate, pyruvate, 3-phosphoglycerate, and dihydroxyacetonephosphate contents. Metabolite concentrations were used with equilibrium constants of triosephosphate isomerase, glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, lactate dehydrogenase, and creatine kinase to estimate cytosolic pH changes during the rest-to-work transition. Magnesium and hydrogen binding were taken into account. Limits to this approach include errors in the intermediate measurements and uncertainties in values of the equilibrium constants. The former leads to maximum errors of +/- 0.15 pH units, whereas the latter affects the absolute pH value but not estimates of the changes in pH. The estimated pH increases from a resting value of 7.05 to approximately 7.8 by 5 s of stimulation and then falls to a pH value of approximately 6.5 after 3 min of stimulation. The results are consistent with previous studies but permit identification of a larger early alkaline shift. Potential causes for the pH changes are discussed.
在4Hz的抽搐收缩开始后5、10、15、30、60和180秒，通过快速冷冻技术从血管隔离的自体灌注犬股薄肌中取样肌肉，分析其磷酸肌酸、肌酸、ATP、乳酸、丙酮酸、3-磷酸甘油酸和磷酸二羟丙酮含量。代谢物浓度与磷酸丙糖异构酶、甘油醛-3-磷酸脱氢酶、磷酸甘油酸激酶、乳酸脱氢酶和肌酸激酶的平衡常数一起用于估计从静息到工作转变期间的胞质pH变化。考虑了镁和氢的结合。这种方法的局限性包括中间测量的误差和平衡常数数值的不确定性。前者导致最大误差为±0.15pH单位，而后者影响绝对pH值，但不影响pH变化的估计。估计pH值从静息值7.05在刺激5秒时增加到约7.8，然后在刺激3分钟后降至约6.5的pH值。结果与先前的研究一致，但允许识别出更大的早期碱性偏移。讨论了pH变化的潜在原因。
