Effect of liposomes containing cholesterol on adenylate cyclase activity of cultured mammalian fibroblasts

Data from an incubation study of liposomes prepared with cholesterol and dipalmitoyl phosphatidylcholine and subclones of NRK 5W are consistent with the view that membrane cholesterol content plays a role in controlling the activity of some plasma membrane enzymes.

Abstract

Liposomes prepared with cholesterol and dipalmitoyl phosphatidylcholine were incubated with a clone of normal rat kidney fibroblast of cells in culture. The cells took up [14C]cholesterol in proportion to the concentration of liposomes in the incubation medium, and the uptake increased with time over the four hours of study. Two cell membrane enzymes, adenylate cyclase and (Na+ + K+)-ATPase, exhibited decreased activity after treatment with cholesterol-containing liposomes. The decrease in adenylate cyclase activity was directly proportional to the uptake of [14C]cholesterol. When a variety of subclones of NRK 5W were examined some were found to respond to cholesterol treatment and some did not. These data are consistent with the view that membrane cholesterol content plays a role in controlling the activity of some plasma membrane enzymes.