DIFFERENTIAL REGULATION BY TRANSFORMING GROWTH FACTOR‐β1 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.