Dilator prostanoid-induced cyclic AMP formation and release by cerebral microvascular smooth muscle cells: inhibition by indomethacin.
The effect of indomethacin on dilator prostanoid receptor-mediated cAMP formation was investigated using primary cultures of vascular smooth muscle cells from the newborn pig cerebral microvessels. Cerebral microvascular smooth muscle cells responded to dilator prostanoids (iloprost > PGE2) by increasing cAMP formation and release into the media (EC50 = 2 x 10(-8) M and 2 x 10(-7) M for iloprost and PGE2, respectively). Indomethacin inhibited iloprost- and PGE2-evoked increases in cAMP formation (IC50 = 10(-4) M) and release (IC50 = 10(-6) M) by microvascular smooth muscle cells (maximal inhibition 80-90%), whereas isoproterenol-induced cAMP formation was only slightly attenuated at the highest concentration of indomethacin used (10(-3) M). Aspirin was much less effective in inhibiting dilator prostanoid-induced cAMP formation and release by the cells. Direct analysis of prostacyclin receptor sites using [3H]iloprost as the ligand revealed saturable, high affinity (ED50 = 2 x 10(-8) M) and reversible binding to the membranes isolated from cerebrovascular smooth muscle cells. Indomethacin dose-dependently inhibited [3H]iloprost receptor binding (ID50 = 10(-4) M; maximal inhibition, 70%). The present data suggest that combination of highly effective inhibition of prostaglandin H synthase and receptor binding resulting in inhibition of dilator prostanoid-mediated cAMP formation in target cells may contribute to the increased efficacy of indomethacin compared with other prostaglandin H synthase inhibitors in blocking certain vasodilator responses associated with prostanoids.
Parfenova
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H
Department of Physiology/Biophysics, University of Tennessee, Memphis.
Hsu
P
P
Leffler
C W
CW
D015121:6-Ketoprostaglandin F1 alpha / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D001241:Aspirin / Q000494:pharmacology; D001921:Brain / Q000098:blood supply*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000378:metabolism; D004789:Enzyme Activation; D016285:Iloprost / Q000494:pharmacology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology*; D008833:Microcirculation; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D044006:Receptors, Epoprostenol; D011982:Receptors, Prostaglandin / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects; D013552:Swine
D044006:Receptors, Epoprostenol; D011982:Receptors, Prostaglandin; D015121:6-Ketoprostaglandin F1 alpha; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D006152:Cyclic GMP; D016285:Iloprost; D015232:Dinoprostone; D001241:Aspirin; D007213:Indomethacin