Timmons J A, Poucher S M, Constantin-Teodosiu D, Worrall V, MacDonald I A, Greenhaff P L
Department of Physiology and Pharmacology, University Medical School, Queens Medical Center, Nottingham, United Kingdom.
Am J Physiol. 1996 Mar;270(3 Pt 1):E400-6. doi: 10.1152/ajpendo.1996.270.3.E400.
The metabolic effects of partial ischemia on canine skeletal muscle were examined during 20 min of isometric contraction. A reduction in blood flow of approximately 75% resulted in an approximate 40% reduction in contractile function. Muscle lactate accumulation and phosphocreatine (PCr) hydrolysis were greater during ischemia, indicating a greater reliance on anaerobic ATP regeneration. Pyruvate dehydrogenase transformation to its active form (PDCa) during contraction was not affected by ischemia, such that PDCa did not appear to be a determinant of skeletal muscle fatigue. Acetylcarnitine concentration was greater during ischemic contraction and inversely correlated with PCr concentration (r = -0.79, P<0.01). Furthermore, acetylcarnitine accumulation and PCr degradation correlated with the degree of skeletal muscle fatigue (r = 0.56, P<0.05 and r = 0.70, P<0.01, respectively). Thus the greater the acetyl group oxidation, the lesser the contribution from anaerobic ATP provision and, subsequently, the smaller the degree of muscle fatigue observed. The metabolic characteristics of this model of ischemic muscle contraction are indistinguishable from the normal metabolic responses observed with increasing contractile intensity.
在等长收缩20分钟期间，研究了部分缺血对犬骨骼肌的代谢影响。血流量减少约75%导致收缩功能降低约40%。缺血期间肌肉乳酸积累和磷酸肌酸（PCr）水解增加，表明对无氧ATP再生的依赖性更大。收缩期间丙酮酸脱氢酶向其活性形式（PDCa）的转变不受缺血影响，因此PDCa似乎不是骨骼肌疲劳的决定因素。缺血收缩期间乙酰肉碱浓度更高，且与PCr浓度呈负相关（r = -0.79，P<0.01）。此外，乙酰肉碱积累和PCr降解与骨骼肌疲劳程度相关（分别为r = 0.56，P<0.05和r = 0.70，P<0.01）。因此，乙酰基氧化程度越高，无氧ATP供应的贡献就越小，随后观察到的肌肉疲劳程度就越小。这种缺血性肌肉收缩模型的代谢特征与随着收缩强度增加而观察到的正常代谢反应无法区分。
