PROTEIN-KINASE-C (PKC)-MEDIATED PROTEIN-PHOSPHORYLATION IN RAT AORTICSMOOTH-MUSCLE CELLS IS ENHANCED BY ALLYLAMINE

The profile of endogenous protein phosphorylation mediated by protein kinase C (PKC) was examined in cell fractions prepared from subculture d aortic smooth muscle cells (SMCs) isolated from rats treated with 70 mg/kg allylamine (AAM) or tap water for 20 days. Increased phosphoryl ation of endogenous proteins was observed under unstimulated condition s in the particulate, but not cytosolic, fraction of cells from AAM-tr eated animals (i.e. AAM cells) relative to control cells. Although the same phosphorylation bands were observed in the particulate or cytoso lic fraction of control and AAM cells following phorbol ester stimulat ion of the enzyme, enhanced PKC-mediated phosphorylation was observed in both fractions of AAM cells relative to control cells. Measurements of exogenous histone Type III-S phosphorylation by PKC following in v itro exposure of naive SMCs to 100 mu M AAM for up to 60 min revealed that AAM selectively increased histone phosphorylation in the cytosoli c fraction of SMCs. These results demonstrate that AAM treatment enhan ces PKC-mediated protein phosphorylation in rat aortic SMCs and raise the possibility that such alterations participate in the angiotoxic re sponse to AAM.