AJP - Cell Physiology, Vol 253, Issue 5 C672-C678, Copyright © 1987 by American Physiological Society
Effect of plasma membrane fluidity on serotonin transport by endothelial cells
E. R. Block and D. Edwards
Research Service, Veterans Administration Medical Center, Gainesville, Florida.
To evaluate the effect of plasma membrane fluidity of lung endothelial
cells on serotonin transport, porcine pulmonary artery endothelial cells
were incubated for 3 h with either 0.1 mM cholesterol hemisuccinate, 0.1 mM
cis-vaccenic acid, or vehicle (control), after which plasma membrane
fluidity and serotonin transport were measured. Fluorescence spectroscopy
was used to measure fluidity in the plasma membrane. Serotonin uptake was
calculated from the disappearance of [14C]-serotonin from the culture
medium. Cholesterol decreased fluidity in the subpolar head group and
central and midacyl side-chain regions of the plasma membrane and decreased
serotonin transport, whereas cis-vaccenic acid increased fluidity in the
central and midacyl side-chain regions of the plasma membrane and also
increased serotonin transport. Cis-vaccenic acid had no effect on fluidity
in the subpolar head group region of the plasma membrane. These results
provide evidence that the physical state of the central and midacyl chains
within the pulmonary artery endothelial cell plasma membrane lipid bilayer
modulates transmembrane transport of serotonin by these cells.
