Reduced Calcium-Dependent Proteinase Activity in Cimaterol-Induced Muscle Hypertrophy in Lambs

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Abstract
The purpose of this study was to reveal the possible relationships between total Ca2+-dependent proteinase (CDP) and micromolar-Ca2+-dependent proteinase (µM CDP) activity and cimaterol-induced hypertrophy of skeletal muscle. Dietary administration of 10 ppm cimaterol to finishing lambs reduced (µM CDP activity in longissimus muscle (LD) by 55% (P < .01) and 70% (P < .02) after 3 and 6 wk of treatment, respectively. Total CDP activity was unaffected by cimaterol at both treatment intervals. The reduced µM CDP activity was not associated with a reduced yield of enzyme extract from the muscle. Cimaterol treatment increased the cross-sectional area of the LD by 23.5% at 3 wk and by 35.6% at 6 wk (P < .001). Cimaterol also increased (P < .001) the masses of semitendinosus, semimembranosus and biceps femoris by 26%, 32.4% and 24.5%, respectively. These results suggest that cimaterol-induced muscle hypertrophy may be attained in part by reduction of myofibrillar protein degradation. Copyright © 1988. American Society of Animal Science . Copyright 1988 by American Society of Animal Science