T.P.10 The acute effects of curcumin exposure on skeletal muscle contractile function

Abstract

Curcumin is a component in the Asian spice turmeric which has demonstrated anti-inflammatory, anti-oxidant and anti-cancer effects in animal models of human disease. It has also been shown to alleviate the dystropathology in mdx mice. However, in vitro studies on isolated sarcoplasmic reticulum (SR) vesicles indicate that curcumin has inhibitory effects on SR function which may adversely affect muscle contraction. The aim of this study was to investigate the specific effects of curcumin on skeletal muscle contractile function. These experiments, conducted on isolated extensor digitorum longus (EDL) muscles from 8week old ARC mice, were approved by the animal ethics committee of the University of Western Australia. Mice were anaesthetized (pentobarbitone, 40mg/kg, IP) and the muscles surgically removed and mounted in an in vitro muscle test system containing mammalian Ringer solution bubbled with carbogen. Measures of contractile function were performed before and after 60min exposure to either 100μM curcumin (dissolved in DMSO) or control solution containing the equivalent DMSO concentration (0.05%). The effect of curcumin on the susceptibility to and recovery from fatigue was also assessed. Curcumin exposure significantly decreased maximum specific force in EDL muscles by 14% compared to control muscles exposed to DMSO alone (curcumin: 19.7±0.7N/cm2, n=6; control: 23.0±1.0N/cm2, n=6, P<0.05). Curcumin had no significant effect on peak twitch force, the time to peak or the 1/2 relaxation time of twitch contractions. The rate of muscle fatigue was significantly reduced after curcumin exposure compared to controls (P<0.01, n=6). This study shows for the first time that (100μM) curcumin exposure significantly affects skeletal muscle contractile function. As the twitch contraction and relaxation times are sensitive to changes in SR function, these results are not consistent with previous findings that curcumin inhibits SR Ca2+ handling in SR vesicles.