DEVELOPMENTALLY-REGULATED TRANSFORMING GROWTH-FACTOR-BETA-1 ACTION ONVASCULAR SMOOTH-MUSCLE GROWTH IN THE SHR

1. This study examined the effects of transforming growth factor-beta 1 (TGF-beta 1) on platelet-derived growth factor-BB (PDGF-BB)-stimulat ed proliferation of vascular smooth muscle cells (VSMC) isolated from aortic tissue of 1, 4 and 12 week old spontaneously hypertensive rats (SHR). 2. In 1 week old SHR, TGF-beta 1 inhibited by about 60% VSMC pr oliferation stimulated by PDGF-BB; this inhibitory action of TGF-beta 1 was absent in VSMC isolated from 4 week old, prehypertensive SHR. In contrast, TGF-beta 1 potentiated by about 125% the mitogenic activity of PDGF-BB in VSMC cultures from adult SHR. 3. Age-dependent alterati ons in the action of TGF-beta 1 suggests an important role for TGF-bet a 1 in the development of vascular hypertrophy from adolescence onward s in the SHR.