REGULATION BY PROTEIN-KINASE-C OF TRANSFORMING GROWTH FACTOR-BETA(1) ACTION ON THE PROLIFERATION OF VASCULAR SMOOTH-MUSCLE CELLS FROM SPONTANEOUSLY HYPERTENSIVE RATS

I, This study examined the role of protein kinase C (PKC) on the actio n 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 epiderm al 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 vascula r hypertrophy that develops in the SHR.