Abscisic acid increases lipid bilayer permeability to cations as studied by phosphorus-31 NMR

Using a 31P-NMR lanthanide shift technique, abscisic acid is shown to enhance the permeability to praeseodymium of lipid bilayers composed of 80 mol% phosphatidylcholine and 20 mol% phosphatidylethanolamine. Praeseodymium permeability is immeasurably slow in the absence of the hormone whether or not phosphatidylethanolamine is present in the bilayers. Only in the presence of abscisic acid is praeseodymium permeability observed, the effect being significantly greater when phosphatidylethanolamine is present. These results substantiate prior reports from nonelectrolyte permeability studies that abscisic acid interacts with phosphatidylethanolamine in lipid bilayers.