Vasorelaxing effects of prostaglandin I2 on the canine basilar and coronary arteries.
The effects of prostaglandin (PG) I2 on canine basilar and coronary arteries were studied. PGI2 caused a relaxation from the basal level more effectively in the endothelium-intact preparations of the coronary artery than in those of the basilar artery. The PGI2-induced relaxation in the basilar artery was enhanced by removal of the endothelium, and by treatment with indomethacin (10(-6) M), aspirin (5 X 10(-5) M), both cyclooxygenase inhibitors, OKY-046 (3 X 10(-5) M) and RS-5186 (10(-6) M), both thromboxane (TX) A2 synthetase inhibitors and ONO-3708 (10(-8) M), a TXA2 antagonist. The enhancing effects of removal of the endothelium and treatment with indomethacin and aspirin on the PGI2-induced relaxation were greater than those of treatment with OKY-046, RS-5186 and ONO-3708. The PGI2-induced relaxation in the coronary artery was not affected by removal of the endothelium, treatment with indomethacin (10(-6) M) or methylene blue (10(-6) M). In the endothelium-removed preparations precontracted with a TXA2 agonist, PGI2-induced relaxation was less in the basilar artery than in the coronary artery. The present experiments suggest that endothelium-derived factors (TXA2 and other cyclooxygenase products) counteract the vasorelaxing effect of PGI2 in the canine basilar artery, but not in the coronary artery.
Shirahase
H
H
Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan.
Usui
H
H
Manabe
K
K
Kurahashi
K
K
Fujiwara
M
M
D000818:Animals; D001488:Basilar Artery / Q000187:drug effects*; D003331:Coronary Vessels / Q000187:drug effects*; D004285:Dogs; D004730:Endothelium, Vascular / Q000502:physiology; D011464:Epoprostenol / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008689:Methacrylates / Q000494:pharmacology; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects*
D008689:Methacrylates; D013928:Thromboxane A2; C049855:ONO 3708; D011464:Epoprostenol; C034364:ozagrel; D007213:Indomethacin