Biochemical and histochemical study of hind limb muscles of aged rats after immobilization and remobilization

Biochemical and histochemical analyses of the lower extremity of aging skeletal rats were done to investigate the effect of 4 weeks of immobilization and 4 and 8 weeks of recovery. Biochemical parameters included specific activity of several enzymes: Acid phosphatase (ACP), Alkaline phosphatase (ALP), Creatine phosphokinase (CPK), protein concentration (determined by Lowry procedure), protein carbonyl oxidation (PCO, determined by carbonyl assay) and lipid peroxidation (LPX). Histochemical analyses to differentiate between fiber types included myosin ATPase, and Succinate Dehydrogenase (SDH). Analysing the effect of immobilization and the recovery capability of old muscles we can concluded that: a) The activity of these enzymes in immobilized hindlimb muscles were significantly interrupted and characterized by decreasing activity of CPK, mATPase, and SDH and by increasing activity of ACP and ALP; b) Accumulation of PCO and LPX was significantly in immobilized leg; c) After 4 and 8 weeks of re-mobilization there is a non complete recovery in biochechemical and histochemical parameters; d) yet, not all the hindlimb muscles are equally affected by the immobilization and re-mobilization procedure. Gastrocnemius and Plantaris muscles were affected the most. The conclusion is that 4 weeks of immobilization caused an irreversible damage of old muscles and their capacity to recover after 4 and 8 weeks is limited.