Effects of 4 wk of hindlimb suspension on skeletal muscle mitochondrial respiration in rats

Laboratoire de Physiologie des Interactions, Service d'Exploration de la Fonction Respiratoire, Hôpital Arnaud de Villeneuve, 34295 Montpellier Cedex 5, France Yajid, Fatima, Jacques G. Mercier, Béatrice M. Mercier, Hervé Dubouchaud, and Christian Préfaut. Effects of 4 wk of hindlimb suspension on skeletal muscle mitochondrial respiration in rats. J. Appl. Physiol. 84(2): 479-485, 1998. We investigated in rats the effect of 4 wk of hypodynamia on the respiration of mitochondria isolated from four distinct muscles [soleus, extensor digitorum longus, tibial anterior, and gastrocnemius (Gas)] and from subsarcolemmal (SS) and intermyofibrillar (IMF) regions of mixed hindlimb muscles that mainly contained the four cited muscles. With pyruvate plus malate as respiratory substrate, 4 wk of hindlimb suspension produced an 18% decrease in state 3 respiration for IMF mitochondria compared with those in the control group ( P < 0.05). The SS mitochondria state 3 were not significantly changed. Concerning the four single muscles, the mitochondrial respiration was significantly decreased in the Gas muscle, which showed a 59% decrease in state 3 with pyruvate + malate ( P