Endothelium-dependent contraction induced by platelet-derived substances in canine basilar arteries.
The supernatant obtained from platelet-suspension incubated with thrombin caused contractions in both intact and endothelium-removed canine basilar arteries. Cyproheptadine (5 x 10(-7) M), which reduced the serotonin-induced contraction to about 20%, attenuated the supernatant-induced contraction to 51% in intact arteries and to 24% in endothelium-removed arteries. In both absence and presence of cyproheptadine, the supernatant-induced contraction of intact arteries was significantly larger than that of endothelium-removed arteries. The cyproheptadine-resistant contraction by the supernatant of intact arteries was attenuated by aspirin, OKY-046 (a thromboxane A2 synthetase inhibitor) and ONO-3708 (a thromboxane A2 antagonist), whereas such contraction of endothelium-removed arteries was not affected by these agents. The concentrations of serotonin, ATP and ADP in the supernatant used here were approximately 3, 67 and 44 micrograms/ml, respectively. The mixed solution of serotonin, ATP and ADP, at the same concentrations as the supernatant, also induced cyproheptadine-resistant, endothelium-dependent contractions in intact arteries. The contraction induced by the mixed solution in intact arteries was also attenuated by aspirin, OKY-046 and ONO-3708. The present experiments indicate that the supernatant causes endothelium-dependent contraction in canine cerebral arteries and that platelet-derived ATP and ADP contribute to this contraction.
Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan.
H
H
Shirahase
H
H
Usui
H
H
Shimaji
K
K
Kurahashi
M
M
Fujiwara
D000244:Adenosine Diphosphate / Q000032:analysis / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000032:analysis / Q000494:pharmacology; D000818:Animals; D001488:Basilar Artery / Q000187:drug effects / Q000502:physiology*; D001792:Blood Platelets / Q000737:chemistry / Q000502:physiology*; D003533:Cyproheptadine / Q000494:pharmacology; D004285:Dogs; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D008297:Male; D012701:Serotonin / Q000032:analysis / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology; D013928:Thromboxane A2 / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects*
D003533:Cyproheptadine; D012701:Serotonin; D013928:Thromboxane A2; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D013917:Thrombin