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Are there α‐adrenoceptors in the young chick atria?
Author(s) -
Tayo Fola M.
Publication year - 1984
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.1476-5381.1984.tb10077.x
Subject(s) - phentolamine , isoprenaline , propranolol , atenolol , chronotropic , antagonist , medicine , endocrinology , inotrope , chemistry , contraction (grammar) , contractility , blockade , atrium (architecture) , heart rate , stimulation , receptor , blood pressure , atrial fibrillation
1 The effect of noradrenaline and isoprenaline were studied in the 15‐day old chick atria. Noradrenaline increased both the rate and force of atrial contractions whilst isoprenaline only slightly increased force at very high concentrations. 2 The increase in force after noradrenaline and isoprenaline was reduced by phentolamine, an α‐adrenoceptor antagonist. The β‐antagonist, propranolol and the cardioselective β 1 ‐adrenoceptor antagonist, atenolol, did not reduce the positive inotropy. Noradrenaline‐induced positive chronotropy was, however, resistant to both α‐ and β‐adrenoceptor blockade. 3 It is concluded that the force of contraction of the chick atria may be α‐adrenoceptor‐mediated whilst the rate seems to be mediated by a mechanism sensitive to noradrenaline but insensitive to α‐and β‐adrenoceptor blockade.