Masato Tsuboi and Shigetoshi Chiba
Department of Pharmacology, Shinshu University School of Medicine, Matsumoto
390-8621, Japan
Abstract: We investigated the effects of a continuous infusion
of adenosine on responses of sinus rate and developed tension to bolus injections
of adenosine and acetylcholine in isolated, blood-perfused canine right
atria. Each drug was directly injected into the sinus node artery of the
isolated atrium. During adenosine infusions, the negative chronotropic and
inotropic responses to bolus injections of adenosine were significantly
inhibited in a dose-related manner, while the negative responses to administered
acetylcholine were consistently potentiated. These results indicate that
adenosine infusion has an acute desensitizing action on subsequent bolus
adenosine, although the cholinergic action is enhanced by a continuous infusion
of adenosine.
Keywords: Adenosine infusion, Dog right atria, Desensitization