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Inhibition of cardiac sympathetic neurotransmission by histamine in the dog is mediated by H 1 ‐receptors
Author(s) -
Kimura T.,
Satoh S.
Publication year - 1983
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.1476-5381.1983.tb09427.x
Subject(s) - histamine , cimetidine , medicine , metiamide , chronotropic , endocrinology , stimulation , histamine h2 receptor , heart rate , receptor , antagonist , blood pressure
1 The role of histamine H 1 ‐ and H 2 ‐receptors in mediating prejunctional inhibition of cardiac sympathetic neurotransmission and histamine‐induced coronary vasodilatation were investigated in perfused dog hearts in situ . 2 Intra‐arterial injections of histamine into the right coronary artery during the resting state caused slightly positive chronotropic responses in doses larger than 1 μg. 3 Histamine in doses of 0.1 to 10 μg into the right coronary artery reduced the tachycardia resulting from electrical stimulation of the cardiac sympathetic nerves. 4 Intra‐coronary infusions of chlorpheniramine (300 μg/min) significantly reduced the histamine‐induced depression of cardiac nerve stimulation. The effects of cimetidine (300 μg/min) and metiamide (300 μg/min) were less pronounced. 5 Histamine (1 to 10 μg) further increased heart rate resulting from the continuous intra‐coronary infusion of noradrenaline (1 or 3 μg/min). 6 Intra‐arterial injections of histamine (0.1 to 10 μg) caused an increase in coronary blood flow in a dose‐dependent manner. This was partially inhibited by intra‐coronary infusion of chlorpheniramine (10 to 300 μg/min) and by cimetidine (10 to 300 μg/min). The combination of both drugs (10 to 100 μg/min of each) caused a larger inhibition. 7 The present results suggest that the histamine‐induced depression of heart rate during cardiac sympathetic nerve stimulation is due to a prejunctional effect mediated mainly by H 1 ‐receptors. Histamine‐induced coronary vasodilatation in the dog is mediated both by H 1 ‐ and H 2 ‐receptors.