Background: Metabolic derangements in type 2 diabetes mellitus (T2DM) are likely to affect skeletal muscle contractile functions adversely. Levo-carnitine improves muscle contractile functions in healthy humans and rats and corrects metabolic derangements in T2DM. Therefore, it is likely to improve muscle contractile functions in T2DM as well. This study was designed to determine the effect of levo-carnitine on serum levo-carnitine levels, oxidative stress and contractile parameters of fast muscle in T2DM.
Methods: Ninety Sprague-Dawley rats were randomly divided into three equal groups. Healthy rats served as the controls, while T2DM was induced in diabetic and carnitine groups. The carnitine group was administered levo-carnitine 200 mg/kg/day intraperitoneally for 6 days. At 28th day, extensor digitorum longus muscles were removed and their functions were assessed using iWorx data acquisition unit (AHK/214). Blood obtained by intra-cardiac sampling at 28th day was used for estimation of serum malondialdehyde (MDA) and levo-carnitine levels.
Results: Maximum isometric twitch tension, time-to-peak twitch tension and time-to-relax to 50% of the peak twitch tension were not significantly different amongst the groups. Carnitine group showed significant improvement in maximum fused tetanic tension, maximum fused tetanic tension after fatigue protocol and recovery from fatigue after 5 minutes of rest period compared to the diabetic group. Serum MDA levels were reduced, while serum levo-carnitine levels were elevated significantly in carnitine group as compared to the diabetic group.
Conclusion: Levo-carnitine supplementation increases serum levo-carnitine levels which decreases oxidative stress. This action improves contractile force but delays fatigue in fast muscles of diabetic rats.
Keywords: Type 2 diabetes mellitus; Levo-carnitine; Fast muscles; Contractile functions; Oxidative stress.