REGULATION OF A COMMON, LOW-AFFINITY BINDING-SITE FOR PRIMARY PROSTANOIDS ON BOVINE AORTIC ENDOTHELIAL-CELLS

Bovine aortic endothelial cells contain a prostaglandin site which bin ds with similar low-affinity PGE(2), PGF(2 alpha) and the thromboxane agonist U-46619. Treatment of the cells with agents that increase the level of cellular cAMP such as forskolin, a direct activator of adenyl ate cyclase or IBMX, a phosphodiesterase inhibitor, decreased the bind ing of PGE(2) to the cells. Addition of dibutyryl cAMP to intact cells caused a quick reduction in PGE(2) binding with a half time of less t han 2 min. The reduction in PGE(2) binding was completely reversible a fter removing the dibutyryl cAMP. The reduction in PGE(2) binding afte r addition of dibutyryl cAMP to the intact cells was also observed aft er a mechanical disruption of the cells or after permeabilization with digitonin. Incubation of the cells with myristoylated PKI(14-22) amid e, a specific protein kinase A inhibitor, resulted in partial suppress ion of the reduction of PGE(2) binding by dibutyryl cAMP. Pretreatment of intact cells for 24 h with 10(-6) M PGE(2) or a PKC activator did not reduce the specific binding of [H-3]-PGE(2). These results suggest that PKA, but not PKC, is involved in a fast reversible regulation of the common prostanoid receptor on bovine endothelial cells. (C) 1998 Elsevier Science B.V.