Endothelium-independent and -dependent contractions induced by endothelin-1 in canine basilar arteries.
Endothelium-dependence of contractile responses to endothelin-1 was examined in isolated canine basilar arteries. Within 2 hrs after mounting tissue preparations, endothelin-1 (10(-9) M) caused a monophasic tonic contraction that developed very slowly and was sustained in intact and endothelium-removed arteries. More than 5 hrs after tissue mounting, endothelin-1 (10(-9) M) caused a biphasic contraction consisting of phasic and tonic components in intact arteries, and caused a monophasic tonic contraction in endothelium-removed arteries. This phasic component was significantly decreased by aspirin (5 x 10(-5) M,), OKY-046 (10(-5) M) (a TXA2 synthetase inhibitor) and ONO-3708 (10(-8) M) (a TXA2 antagonist). The present experiments demonstrate that endothelin-1 causes an endothelium-independent tonic contraction and an endothelium-dependent phasic contraction in canine basilar arteries, and suggest that TXA2 plays a role as an endothelium-derived contracting factor.
Shirahase
H
H
Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan.
Usui
H
H
Shimaji
H
H
Kurahashi
K
K
Fujiwara
M
M
D000818:Animals; D001158:Arteries / Q000187:drug effects* / Q000502:physiology; D001241:Aspirin / Q000494:pharmacology; D001488:Basilar Artery; D004285:Dogs; D016232:Endothelins / Q000494:pharmacology*; D004727:Endothelium / Q000502:physiology*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008689:Methacrylates / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects*
D016232:Endothelins; D008689:Methacrylates; D013928:Thromboxane A2; C049855:ONO 3708; C034364:ozagrel; D001241:Aspirin