Interaction of Lipids with the Plasma Membrane of Sperm Cells. II. Evidence of a Membrane Thermotropic Transition

Abstract

Cholesterol and phosphatidylcholine uptake from dipalmitoyl-phosphatidylcholine liposomes by rabbit spermatozoa showed a complex dependence on temperature in these experiments. At 5° and 20°C, the rate of lipid uptake correlated with temperature. However, from 20° to 37°C uptake did not evidently increase. The result is interpreted as evidence of a thermotropic transition in the sperm plasma membrane. Data are presented showing incorporation of these lipids, especially that of cholesterol, into sperm plasma membrane.

Key Words:

• Association kinetics
• Cholesterol
• Phospholipid
• Sperm plasma membrane.