Role of adenosine receptors in the paradoxic bradycardia response of rats to inferior vena cava occlusion during an infusion of isoproterenol

In susceptible humans, vasodepressor reactions are induced by restriction of venous return (upright tilting) and administration of isoproterenol. Because paradoxic bradycardia is a major manifestation of vasodepressor reactions, and allowing for extrapolation between paradoxic bradycardia in rats an...

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Bibliographic Details
Published in:Circulation (New York, N.Y.) N.Y.), 1998-09, Vol.98 (12), p.1228-1235
Main Authors: WAXMAN, M. B, ASTA, J. A
Format: Article
Language:English
Subjects:
Adenosine - pharmacology
Adenosine Triphosphate - pharmacology
Aminophylline - pharmacology
Animals
Biological and medical sciences
Blood Pressure - drug effects
Bradycardia - etiology
Cardiac dysrhythmias
Cardiology. Vascular system
Dipyridamole - pharmacology
Heart
Heart Rate - drug effects
Isoproterenol - pharmacology
Male
Medical sciences
Rats
Rats, Wistar
Receptors, Purinergic P1 - drug effects
Vagus Nerve - physiology
Vena Cava, Inferior - physiology
Xanthines - pharmacology
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Summary:In susceptible humans, vasodepressor reactions are induced by restriction of venous return (upright tilting) and administration of isoproterenol. Because paradoxic bradycardia is a major manifestation of vasodepressor reactions, and allowing for extrapolation between paradoxic bradycardia in rats and vasodepressor reactions, we examined whether adenosine receptors mediate the paradoxic bradycardia reaction. Paradoxic bradycardia was induced in rats by inferior vena cava occlusion during an isoproterenol infusion. We studied whether dipyridamole, an adenosine transport inhibitor, and aminophylline (nonselective) or DPCPX (selective) A1 antagonists augmented or inhibited paradoxic bradycardia, respectively, during inferior vena cava occlusion. The maximum changes in R-R during 60 seconds of inferior vena cava occlusion were that (1) in control, the rate accelerated (DeltaR-R, -9.7+/-0.8 ms, P
ISSN:0009-7322
1524-4539
DOI:10.1161/01.CIR.98.12.1228