Two different isolated skeletal muscles of Japanese quail were used. The influence of branched chain amino acids on the fractional rate of protein synthesis (FSR) was evaluated using 14C-tyrosine. The addition of 0.5 mM valine, leucine or isoleucine to the incubation medium significantly decreased (P<0.05) the value of FSR in extensor metacarpalis radialis. In the ambiens muscle only the application of leucine increased the FSR significantly while valine and isoleucine were without any effect., J. Antalíková, J. Jankela, M. Baranovská., and Obsahuje bibliografii