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Antiarrhythmic action of rilmenidine on adrenaline‐induced arrhythmia via central imidazoline receptors in halothane‐anaesthetized dogs
Author(s) -
Mammoto Tadanori,
Kamibayashi Takahiko,
Hayashi Yukio,
Yamatodani Atsushi,
Takada Koji,
Yoshiya Ikuto
Publication year - 1996
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.1476-5381.1996.tb15348.x
Subject(s) - rilmenidine , imidazoline receptor , idazoxan , chemistry , pharmacology , rauwolscine , halothane , medicine , prazosin , endocrinology , agonist , antagonist , receptor , organic chemistry
1 To elucidate the role of central imidazoline receptors in the genesis of adrenaline‐induced arrhythmias under halothane anaesthesia, we investigated the effects of rilmenidine, a selective agonist at imidazoline receptors, on this type of arrhythmia in dogs. Rilmenidine (1, 3, 10 μg kg −1 , i.v.) did not affect basal haemodynamic parameters (heart rate and blood pressure), but dose‐dependently inhibited adrenaline‐induced arrhythmias under halothane anaesthesia. 2 Although, rilmenidine has a weak affinity for α 2 ‐adrenoceptors, pretreatment with idazoxan (10 μg kg −1 , intracistenally i.c.), an imidazoline receptor antagonist which has also α 2 ‐adrenoceptor blocking potency, blocked the antiarrhythmic effect of rilmenidine (10 μg kg −1 , i.v.). In contrast, pretreatment with rauwolscine (20 μg kg −1 , i.c.), a classical α 2 ‐adrenoceptor antagonist with little affinity for imidazoline receptors, did not affect the effect of rilmenidine (10 μg kg −1 , i.v.). Furthermore, bilateral vagotomy completely blocked the antiarrhythmic action of rilmenidine (10 μg kg −1 , i.v.). 3 It is suggested that the antiarrhythmic action of rilmenidine is due to the activation of central imidazoline receptors and that vagal tone is critical for this action of rilmenidine.