Phorbol myristate acetate inhibits the bradykinin-induced L-nitro-arginine insensitive endothelium-dependent relaxation of bovine coronary artery.
The effects of L-nitro-arginine (LNAG) and phorbol myristate acetate (PMA) were studied in bradykinin-induced relaxations in bovine coronary arteries. In the presence of indomethacin (10 microM), neither LNAG (100 microM) nor PMA (0.1 microM) inhibited the bradykinin-induced relaxations in coronary arterial rings contracted with prostaglandin F2 alpha. However, simultaneous application of LNAG and PMA almost completely abolished the bradykinin-induced relaxation. In a sandwich-method, endothelium-intact coronary arteries (donor vessels) were treated with LNAG or with PMA for 30 min and then placed in close apposition to a denuded ring (assay vessel). Pretreatment of the donor vessels with LNAG, but not with PMA, almost completely abolished the bradykinin-induced relaxations in the assay vessel. In contrast, treatment of the assay vessel with PMA or with LNAG had no effect. These results suggest that bradykinin-induced endothelium-dependent relaxation of bovine coronary artery depends on both the release of nitric oxide and other endothelium-derived relaxing factor(s), which is an extremely labile substance(s), or a non-diffusible factor(s). PMA seems to inhibit the production and/or the release of the latter substance(s).
Obi
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Department of Veterinary Pharmacology, Faculty of Agriculture, Kagoshima University, Japan.
Suzuki
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F
Nishio
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D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001920:Bradykinin / Q000037:antagonists & inhibitors*; D002417:Cattle; D003331:Coronary Vessels / Q000187:drug effects; D015237:Dinoprost / Q000494:pharmacology; D004594:Electrophysiology; D004730:Endothelium, Vascular / Q000502:physiology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism*; D019335:Nitroarginine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D019335:Nitroarginine; D009569:Nitric Oxide; D001120:Arginine; D015237:Dinoprost; D013755:Tetradecanoylphorbol Acetate; D001920:Bradykinin; D007213:Indomethacin