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α 1 ‐Adrenoceptors in the conduction system of rat hearts
Author(s) -
Saito Kazuto,
Suetsugu Tetsuro,
Oku Yoshiya,
Kuroda Atsushi,
Tanaka Hiromitsu
Publication year - 1994
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.1476-5381.1994.tb14759.x
Subject(s) - phentolamine , prazosin , sinoatrial node , atrioventricular node , adrenergic receptor , medicine , electrical conduction system of the heart , isoprenaline , endocrinology , chemistry , propranolol , anatomy , heart rate , electrocardiography , receptor , tachycardia , stimulation , blood pressure , antagonist
1 We have characterized α 1 ‐adrenoceptor in the conduction systems of the rat heart by quantitative autoradiography. 2 Consecutive 20 μm thick sections from a single rat heart containing the sinoatrial (SA) node and atrioventricular (AV) node were incubated with increasing concentrations of [ 3 H]‐prazosin with or without 10 μ m phentolamine. After exposure to 3 H‐Ultrofilm, optical densities corresponding to the SA node and AV node were determined by computerized densitometry after comparison with 3 H standards. 3 The SA node and AV node were stained heavily for cholinesterase and they contained a higher concentration of α 1 ‐adrenoceptors than the adjacent myocardium without a significant change in the affinity. 4 These results support the hypothesis that α 1 ‐adrenoceptors may play an important role not only in inotropism but also in chronotropism of rat hearts.