Circadian variations of the protein metabolism in muscle∗∗

Publisher Website
Google Scholar
Abstract
The protein content of mouse diaphragm at different times of the year, as well as the C14‐leucine incorporation into that protein were studied. Lowry's method was employed for the protein estimation. The aminoacid incorporation was determined one hour after the in vivo administration of C14‐labelled leucine in the previously extracted diaphragmatic protein, with the aid of a liquid scintillation spectrometer. It was found that both, the protein content and the aminoacid incorporation values, depend on the time of the circadian period at which the experiment was performed. The highest values for protein were found during the activity period while the corresponding incorporation ones were located within the resting period. Furthermore, a seasonal variation of the circadian protein rhythm was found. These results stress again the importance of circadian variations in experimental biology.