Regulation by protein kinase C of transforming growth factor-beta 1 action on the proliferation of vascular smooth muscle cells from spontaneously hypertensive rats.

1. This study examined the role of protein kinase C (PKC) on the action of transforming growth factor-beta 1 (TGF-beta 1) to regulate the proliferation of vascular smooth muscle cells (VSMC) isolated from the aorta of the spontaneously hypertensive rat (SHR). 2. Down-regulation of PKC by prolonged exposure to phorbol 12-myristate 13-acetate (PMA) completely inhibited the ability of TGF-beta 1 to potentiate epidermal growth factor-stimulated proliferation of VSMC. 3. In contrast, the inhibitory effect of TGF-beta 1 on serum-stimulated proliferation of VSMC was not altered by PMA action. 4. These results suggest that PKC-dependent signalling pathways involved in the regulation of growth by TGF-beta 1 may be important in any proliferative component of vascular hypertrophy that develops in the SHR.