Differential regulation by transforming growth factor-beta 1 of platelet-derived growth factor-stimulated proliferation of vascular smooth muscle cells from SHR and WKY rats.

1. This study has examined and compared the time-course of action of transforming growth factor-beta 1 (TGF-beta 1) on platelet-derived growth factor-BB-stimulated proliferation of vascular smooth muscle cells isolated from normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). 2. Transforming growth factor-beta 1 inhibited vascular smooth muscle cell proliferation stimulated by platelet-derived growth factor-BB in WKY rats by approximately 60-75%. 3. In contrast, transforming growth factor-beta 1 potentiated an 8-35% growth factor action on cell proliferation in the SHR. 4. Defects in transforming growth factor-beta 1 action may be part of the molecular mechanism responsible for the development of vascular hypertrophy in the SHR.