Phorbol myristate acetate stimulates pinocytosis and membrane spreading in mouse peritoneal macrophages.

Abstract

Phorbol myristate acetate (PMA) at a concentration of 0.01 .mu.g/ml causes an approximately 3-fold increase in surface area of resident, proteose-peptone-elicited and thioglycolate-broth-elicited mouse peritoneal macrophages. Resident and proteose-peptone-elicited macrophages, cultured for 24 h in the presence of PMA, increase their pinocytic rate 2-fold in response to addition of PMA (0.01 .mu.g/ml) to the medium. Thioglycolate-broth-elicited macrophages, cultured for 24 h in the absence of PMA, immediately increase their pinocytic rate 2- to 3.5-fold in response to a single challenge with PMA (0.01 .mu.g/ml). Cytochalasin B, colchicine and podophyllotoxin have only modest inhibitory effects on the basal rate of pinocytosis, and on PMA-induced cellular spreading, but completely block the stimulatory effects of PMA on pinocytosis in thioglycolate-broth-elicited macrophages. Cytochalasin D markedly inhibits basal and PMA-stimulated pinocytosis in these cells. PMA is a useful tool for studying mechanisms of macrophage spreading, and for enhancing the overall rate of pinosome formation.