Thromboxane A 2 receptors are influenced by cell density in cultured rat aortic smooth muscle cells

Abstract

The influence of cell density on the binding characteristics of thromboxane A 2/prostaglandin H 2 (TXA 2/PGH 2) receptors in rat aortic vascular smooth muscle cells in culture were determined using [1S- (1α, 2β (5Z), 3a (1E, 3R ∗), 4α)] - 7 -[3- (3-hydroxy -4- (4'- iodophenoxy)-1-butenyl)-7-oxabicyclo-[2.2.1]heptan-2yl]-5-heptenoic acid ( 125I-BOP). The B max for 125I-BOP was 5,430±139 sites/cell (26.9±5.7 fmoles/mg protein) for cells cultured in 1% fetal calf serum and 2809±830 sites/cell (13.1±2.2 fmoles/mg protein) for cells cultured in 10% fetal calf serum. Cells were allowed to grow to varying densities and then harvested for assay. There was a negative correlation between the B max and the cell density per flask. The K d for I-BOP did not significantly vary in any of the studies. The results demonstrate that cell density plays an important role in influencing the expression of vascular TXA 2/PGH 2 receptors.