Greenhaff P L, Ren J M, Söderlund K, Hultman E
Department of Clinical Chemistry II, Huddinge University Hospital, Karolinska Institute, Sweden.
Am J Physiol. 1991 May;260(5 Pt 1):E713-8. doi: 10.1152/ajpendo.1991.260.5.E713.
The concentrations of glycogen, ATP, and phosphocreatine were analyzed in types I and II muscle fibers separated from biopsy samples of the quadriceps femoris muscle in five healthy volunteers. Muscle samples were obtained before and after 64 s of intermittent electrical stimulation. The experiment was carried out without and with epinephrine (Epi) infusion. Before stimulation the glycogen concentration was 11% higher in type II than in type I fibers (P less than 0.05). During electrical stimulation, rapid glycogenolysis occurred in type II fibers with hardly any detectable glycogenolysis in type I fibers. The calculated rates of glycogenolysis were 0.18 +/- 0.14 and 3.54 +/- 0.53 mmol glucose.kg dry muscle-1.s-1 in types I and II fibers, respectively. Epi infusion increased the rate of glycogenolysis during electrical stimulation in type I fibers (10-fold) but did not enhance the rate in type II fibers (P greater than 0.05). It is considered that, during short-term maximal muscle contraction, rapid muscle glycogenolysis occurs predominantly in type II fibers even though types I and II fibers are recruited and that, when Epi stimulation of glycogenolysis occurs, this is predominantly limited to type I fibers.
对五名健康志愿者股四头肌活检样本中分离出的I型和II型肌纤维中的糖原、三磷酸腺苷（ATP）和磷酸肌酸浓度进行了分析。在间歇性电刺激64秒之前和之后获取肌肉样本。实验在未输注肾上腺素（Epi）和输注肾上腺素的情况下进行。刺激前，II型纤维中的糖原浓度比I型纤维高11%（P<0.05）。在电刺激期间，II型纤维中发生快速糖原分解，而I型纤维中几乎没有可检测到的糖原分解。计算得出的I型和II型纤维中糖原分解速率分别为0.18±0.14和3.54±0.53 mmol葡萄糖·kg干肌肉-1·s-1。输注Epi增加了I型纤维在电刺激期间的糖原分解速率（10倍），但未提高II型纤维的速率（P>0.05）。据认为，在短期最大肌肉收缩期间，即使I型和II型纤维都被募集，快速的肌肉糖原分解主要发生在II型纤维中，并且当发生Epi刺激糖原分解时，这主要限于I型纤维。
