Inhibitory effects of brefeldin A, a membrane transport blocker, on the bradykinin-induced hyperpolarization-mediated relaxation in the porcine coronary artery.
1. To elucidate the mechanism of the relaxation mediated by endothelium-derived hyperpolarizing factors (EDHFs), the effect of brefeldin A, a membrane transport blocker, on cytosolic Ca(2+) concentration ([Ca(2+)]i) and tension was determined in the porcine coronary arterial strips. We also examined the effect of brefeldin A on [Ca(2+)]i in the endothelial cells of the porcine aortic valve. 2. In the presence of 10 microM indomethacin and 30 microM N(G)-nitro-L-arginine (L-NOARG), both bradykinin and substance P induced a transient decrease in [Ca(2+)]i and tension in arterial strips contracted with 100 nM U46619 (thromboxane A2 analogue). A 6 h pre-treatment with 20 microg ml(-1) brefeldin A abolished the bradykinin-induced relaxation, while it had no effect on the substance P-induced relaxation. 3. In the absence of indomethacin and L-NOARG, brefeldin A had no effect on the bradykinin-induced relaxation during the contraction induced by U46619 or 118 mM K(+). 4. The indomethacin/L-NOARG-resistant relaxation induced by bradykinin was completely inhibited by 3 mM tetrabutylammonium (non-specific Ca(2+)-activated K(+) channel blocker), while that induced by substance P was not inhibited by 3 mM tetrabutylammonium or 1 mM 4-aminopyridine (voltage-dependent K(+) channels blocker) alone, but completely inhibited by their combination. 5. Brefeldin A had no effect on the [Ca(2+)]i elevation in endothelial cells induced by bradykinin or substance P. 6. In conclusion, bradykinin produce EDHF in a brefeldin A-sensitive mechanism in the porcine coronary artery. However, this mechanism is not active in a substance P-induced production of EDHF, which thus suggests EDHF to be more than a single entity.
Ohnishi
Y
Y
Division of Molecular Cardiology, Research Institute of Angiocardiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 Japan.
Hirano
K
K
Nishimura
J
J
Furue
M
M
Kanaide
H
H
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D001030:Apamin / Q000494:pharmacology; D001685:Biological Factors / Q000502:physiology; D001920:Bradykinin / Q000494:pharmacology*; D020126:Brefeldin A / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D019335:Nitroarginine / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D026902:Potassium Channel Blockers; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D013373:Substance P / Q000494:pharmacology; D013552:Swine; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*
D001685:Biological Factors; D010455:Peptides; D026902:Potassium Channel Blockers; D000644:Quaternary Ammonium Compounds; D014662:Vasoconstrictor Agents; C067410:endothelium-dependent hyperpolarization factor; D020126:Brefeldin A; D019335:Nitroarginine; D001030:Apamin; D013373:Substance P; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; C064719:iberiotoxin; D015761:4-Aminopyridine; C009405:tetrabutylammonium; D011188:Potassium; D001920:Bradykinin; D002118:Calcium; D007213:Indomethacin