Metabolic studies on the micropinocytic process in endothelial cells

Tufts of capillary endothelium isolated from rat epididymal fat ingest [ 14 C]sucrose by the process of micropinocytosis. Ingestion of sucrose for periods in excess of 30 min was quantitated using the concentration of cellular DNA as a standard. Capillaries incubated in the metabolic inhibitors 2,4-dinitrophenol, NaN 3 , or iodoacetate exhibit a dose-dependent reduction of cellular ATP. Micropinocytic ingestion of [ 14 C]sucrose is not affected by concentrations of these inhibitors which markedly reduce or deplete ATP pools. Pure oxygen or nitrogen atmospheres also have no effect on micropinocytosis. Ingestion of [ 14 C]sucrose is reduced, however, at temperatures lower than 37° or in the presence of Zn 2+ .