1. Angiotensin II (ANG II) increases hepatic RNA synthesis. Because the hormone apparently can be found in the cytoplasm of at least some target cells and because intracellular receptors have been demonstrated for this hormone, we investigated the direct effect of angiotensin II on isolated nuclei.
2. Nuclei were purified from rat liver and then treated for 2 h at 37°C with various concentrations of angiotensin II. Chromatin was then isolated and initiation-site number was estimated by utilizing exogenous Escherichia coli RNA polymerase.
3. Statistically significant increases in initiation-site number were noted in nuclei treated with angiotensin II suggesting that at least part of the hormone's stimulatory effect on RNA synthesis results by this mechanism. Furthermore, these observations suggest a direct nuclear effect of this peptide hormone.