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Effects of α‐ and β‐adrenoceptor blockade on the neurally evoked overflow of endogenous noradrenaline from the rat isolated heart
Author(s) -
Dart A.M.,
Dietz R.,
Hieronymus K.,
Kübler W.,
Mayer E.,
Schömig A.,
Strasser R.
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.tb10100.x
Subject(s) - yohimbine , stimulation , propranolol , desipramine , endogeny , medicine , blockade , endocrinology , heart rate , chemistry , antagonist , receptor , blood pressure , antidepressant , hippocampus
1 β‐Adrenoceptor blockade by propranol (4 × 10 −6 m ) was without effect on the overflow of endogenous noradrenaline from the isolated heart of the rat induced by stimulation of sympathetic nerves for 1 min at 1 and at 4Hz. The increase in heart rate in response to such stimulation was abolished by propranolol treatment. 2 α 2 ‐Adrenoceptor blockade by yohimbine (10 −6 m ) induced approximately a two fold increase in the overflow of endogenous noradrenaline induced by stimulation of sympathetic nerves for 1 min at 1 and at 4 Hz. 3 A combination of yohimbine (10 −6 m ) and desipramine (10 −7 m ) induced a more than 3 fold increase in the overflow of endogenous noradrenaline produced by sympathetic nerve stimulation at 1 and at 4 Hz. Heart rate increases produced by such stimulation were intensified. 4 These results provide no evidence for the feedback stimulation of presynaptic β‐adrenoceptors in this preparation. The action of α 2 ‐blockade was equipotent at stimulation frequencies of 1 and 4 Hz.