Kinetin Increases Water Permeability of Phosphatidylcholine Lipid Bilayers

Kinetin is shown to increase substantially the water permeability of liposomes composed of several types of phosphatidylcholines including the natural phospholipids egg lecithin and asolectin and the synthetic phospholipids dimyristoylphosphatidylcholine and dipalmitoylphosphatidylcholine. Kinetin effects were measured from 16.3 micromolar to 2.4 millimolar at temperatures from 10 degrees C to 50 degrees C and at pH 2.0, 7.0, and 11.0. Temperature studies indicate that kinetin produces a larger increase in water permeability with membranes in the more fluid liquid crystalline state. Kinetin is also shown to enhance [(14)C]glucose permeability and perhaps promotes membrane aggregation. From these experiments, we conclude that kinetin may produce its initial effect by altering the lipid bilayer portion of membranes.