title: Omeprazole-induced relaxation in rat aorta is partly dependent on endothelium.
abstract: We investigated the effect of omeprazole (1 x 10(-5)-3 x 10(-4)M), an inhibitor of H(+),K(+)-ATPase, on rat aortic rings pre-contracted with phenylephrine (10(-6)M). Omeprazole relaxed the tissue in a concentration-dependent manner. Either removal of the endothelium or incubation with nitric oxide (NO) synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME, 3 x 10(-5)M) significantly attenuated the relaxations. Pre-treatment with L-arginine (10(-3)M), but not with D-arginine, reversed the inhibitory action of L-NAME. Indomethacin (10(-6)M) and tetraethylammonium (TEA, 10(-2)M) did not affect the relaxant responses to omeprazole indicating the lack of involvement of cyclooxygenase products and K(+) channels, respectively. These results suggest a role of NO in the mechanism of action of omeprazole.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009853:Omeprazole / Q000494:pharmacology*; D010208:Papaverine / Q000494:pharmacology; D010656:Phenylephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D054328:Proton Pump Inhibitors; D051381:Rats; D019789:Tetraethylammonium / Q000494:pharmacology; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D026902:Potassium Channel Blockers; D054328:Proton Pump Inhibitors; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D010656:Phenylephrine; D019789:Tetraethylammonium; D010208:Papaverine; D009853:Omeprazole; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester; D007213:Indomethacin