The regulation of liver glycogen synthetase D phosphatase by ATP and glucose

Cortisol at a concentration of 5×10^?6M induces profound changes in U.V. absorption spectra of isolated nuclei from rat liver and thymus. The changes occur within the first 10 min of cortisol action. In both types of nuclei, a blue shift of 5–10 nm from the normal absorption maximum at 260–270 nm is evident. In addition, liver nuclei exhibit an elevation of the spectrum at 230–270 nm (increased U.V. absorption), while the spectrum of thymus nuclei becomes flattened. No such changes occur in nuclei exposed to a physiologically inactive hormone (pregnenolone). The results are interpreted as evidence for cortisol-induced perturbations in deoxyribonucleoprotein structure with consequent changes in the degree of condensation of nuclear chromatin.