Hormonal Control of Protein Synthesis in Muscle: An Approach Through the Study of its Circadian Rhythm[*]

Abstract

The in vitro incorporation of C14-leucine into diaphragmatic protein was studied in mice at four-hour intervals for 24 hours, both with and without addition of insulin to the incubation medium. Significant circadian fluctuations were found in both cases when the proteinspecific activity values were plotted as a function of time. Both curves showed their crests and troughs at 00 and 08 hr respectively. On the other hand, insulin effectiveness as regards stimulation of protein synthesis also showed a circadian rhythm, i.e. it rose from no effect at 00 to its largest P value at 20 hr.

Key words

Protein Synthesis - Circadian Rhythms Muscle Metabolism - Insulin

1 This work was partially supported with funds provided by the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina (Grant No. 3477) and Comisión de Investigaciones Cientificas de la Provincia de Buenos Aires.

1 This work was partially supported with funds provided by the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina (Grant No. 3477) and Comisión de Investigaciones Cientificas de la Provincia de Buenos Aires.