Relationship between receptors mediating serotonin (5-HT) contractions in the canine basilar artery to 5-HT1, 5-HT2 and rat stomach fundus 5-HT receptors.
The receptors responsible for contraction to serotonin (5-HT) in the canine basilar artery have not been definitively established to date. Several selective 5-HT2 receptor antagonists (spiperone, ketanserin and LY53857) did not inhibit markedly 5-HT-induced contractions in the canine basilar artery in doses higher than required for substantial inhibition of 5-HT2 receptor-mediated responses. These data suggest that the receptors mediating 5-HT-induced contractions in the basilar artery are not 5-HT2 receptors. Using a series of 5-HT antagonists with relatively high affinity at 5-HT1 sites, over a 1000-fold difference occurred in their ability to block 5-HT receptors in the canine basilar artery, in spite of the similar and high affinity of the antagonists at 5-HT1 binding sites. These data support the contention that 5-HT receptors in the canine basilar artery are not 5-HT1 receptors as defined by ligand binding studies in brain cortical membranes. Similarity of the contractile effects of 5-HT in the rat stomach fundus and in the basilar artery coupled to the previous observations that receptors mediating 5-HT-induced contractions in the fundus were not 5-HT1, 5-HT1A, 5-HT1B or 5-HT2 led us to consider the possibility that 5-HT receptors in the canine basilar artery may resemble those in the rat stomach fundus. The affinity of several 5-HT antagonists determined in the canine basilar artery correlated extremely well (correlation coefficient = 0.96) with the affinities obtained for the same antagonists in the rat stomach fundus.(ABSTRACT TRUNCATED AT 250 WORDS)
M L
ML
Cohen
W E
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Colbert
D000818:Animals; D001488:Basilar Artery / Q000032:analysis*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D005748:Gastric Fundus / Q000032:analysis*; D066298:In Vitro Techniques; D008238:Lysergic Acid Diethylamide / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000032:analysis* / Q000187:drug effects / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects*
D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D012701:Serotonin; D008238:Lysergic Acid Diethylamide