A comparative study of the effects of polyamino acids and dextran derivatives on pinocytosis in the rat yolk sac and the rat peritoneal macrophage

Poly- l -lysine, poly- l -α-ornithine, poly- l -glutamic acid, dextran, DEAE-dextran and dextran sulphate all fail to affect greatly the rate of pinocytic uptake of 125 I-labelled polyvinylpyrrolidone by 17.5-day rat visceral yolk sac or rat peritoneal macrophages cultured in vitro. It is concluded that these agents do not much affect the rate of pinocytic ingestion of liquid. Polycations accelerate the accumulation of colloidal 198 Au in both systems, and this is ascribed to the formation of substrate · modifier complexes which either adsorb to plasma membrane, and thus gain rapid entry, or initiate another mode of endocytosis. Pinocytic uptake of formaldehyde-denatured 125 I-labelled bovine serum albumin was accelerated by poly- l -lysine and poly- l -ga-ornithine in the macrophage, buth inhibited in the yolk sac.