Effects of temperature, metabolic inhibitors and some other factors on fluid-phase and adsorptive pinocytosis by rat peritoneal macrophages.

Low temperature, NaF and 2,4-dinitrophenol could each abolish the pinocytic uptake of 125I-labelled poly(vinylpyrrolidone) or colloidal [198Au]gold by rat peritoneal macrophages cultured in vitro. Cytochalasin B caused only partial inhibition, even at 10 microgram/ml, and colchicine (10 or 25 microgram/ml) inhibited uptake of colloidal [198Au]gold much more than that of 125I-labelled poly(vinylpyrrolidone). Dibutyryl cyclic AMP and ouabain were without effect on uptake of 125I-labelled poly(vinylpyrrolidone), and slight stimulation was seen with ATP and theophylline. Uptake of 125I-labelled poly(vinylpyrrolidone) was abolished by EGTA (5mM), but restored by adding CaCl2 (5mM). The results appear not to support the conventional criteria for the division of pinocytic phenomena into macropinocytosis, requiring a metabolic energy supply and cytoskeletal components, and micropinocytosis, requiring neither.