Angiotensin II-induced proliferation of aortic myocytes in spontaneously hypertensive rats.

In order to determine whether the morphological modifications observed in arterial media of spontaneously hypertensive rats (SHR) could be induced by an abnormal response of the smooth muscle cells to vasoactive agents, we studied the action of angiotensin (Ang) II on cultured aortic smooth muscle cells from both SHR and Wistar-Kyoto rats (WKY). Under our experimental conditions, Ang II exerts a mitogenic action on SHR cells, whereas its effect is very weak on WKY cells. Phospholipase C activation and c-fos and c-myc proto-oncogene expressions induced by Ang II are considerably enhanced in SHR cells, and these abnormalities may be linked to an increased number of Ang II receptors.