Experimental modulation of the plasmalemmal microfluidity. Studies on endothelial and aortic smooth muscle cells.

The microfluidity of cell membranes has been modified experimentally in endothelial cells and smooth muscle cells of bovine or monkey aorta cultured in vitro. Microfluidity was estimated by fluorescence depolarization measurements of diphenyl-hexatriene (DPH)-labelled cells. In both types of cells investigated, the arachidonic acid at concentration of 90 microM induced an increase in the microfluidity by 26-53% whereas the cholesterol at the same concentration produced a decrease in the microfluidity by 16-25%. The oleic acid in the range of 30 to 90 microM increased the monkey smooth muscle cell membranes microfluidity by 21-33% but did not change the microfluidity of endothelial and bovine aortic smooth muscle cells. The stearic acid did not influence the microfluidity of either type of cells under investigation. Cortisol at 90 microM changed the microfluidity of the bovine aortic endothelial cells plasmalemma depending on the incubation time. Possible factors of error in the physical measurements due to the extracellular localization of DPH have been identified.