Premium
5‐Carboxamidotryptamine is a selective agonist at 5‐hydroxytryptamine receptors mediating vasodilatation and tachycardia in anaesthetized cats
Author(s) -
Connor H.E.,
Feniuk W.,
Humphrey P.P.A.,
Perren M.J.
Publication year - 1986
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1986.tb10832.x
Subject(s) - methysergide , bronchoconstriction , ketanserin , medicine , tachycardia , blood pressure , endocrinology , agonist , propranolol , vascular resistance , vasodilation , receptor , serotonin , 5 ht receptor , asthma
1 We have attempted to characterize the 5‐hydroxytryptamine (5‐HT) receptors mediating bronchoconstriction, vasodilatation, vasodepression and tachycardia in anaesthetized cats following bilateral vagosympathectomy and β‐adrenoceptor blockade with propranolol. 2 5‐HT (1–100 μg kg −1 i.v.) caused dose‐related bronchoconstriction and tachycardia but variable and complex effects on diastolic blood pressure and carotid arterial vascular resistance. 3 In contrast, 5‐carboxamidotryptamine (5‐CT; 0.01–1 μg kg −1 i.v.) caused consistent, dose‐related decreases in diastolic blood pressure and carotid arterial vascular resistance and increases in heart rate. 5‐CT did not cause bronchoconstriction. 4 The 5‐HT‐induced bronchoconstriction was dose‐dependently antagonized by methiothepin, methysergide and ketanserin (10–100 μg kg −1 i.v.). The highest doses used of these antagonists did not antagonize bronchoconstriction induced by prostaglandin F 2α . The high potency of all three antagonists indicate a 5‐HT 2 ‐receptor mediated effect. 5 The 5‐HT‐ and 5‐CT‐induced tachycardia as well as the 5‐CT‐induced vasodepressor and carotid arterial vasodilator responses were dose‐dependently antagonized by low doses of methiothepin (10–100 μg kg −1 i.v.) and by high doses of methysergide (100–1000 μg kg −1 i.v.) but were little affected by ketanserin in doses up to 1000 μg kg −1 i.v. These selective effects of 5‐CT appear to be mediated by ‘5‐HT 1 ‐like’ receptors.