Ligand-independent negative chronotropic responses of rat and mouse right atria to beta-adrenoceptor antagonists.

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Varma DR

Ligand-independent negative chronotropic responses of rat and mouse right atria to beta-adrenoceptor antagonists.

Can J Physiol Pharmacol. 1999 Dec;77(12):943-9.

PubMed ID

10606440 [ View in PubMed

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Abstract

Negative chronotropic effects of beta-adrenoceptor (betaAR) antagonists on right atria from reserpine-treated rats and mice were determined as a test of their inverse agonist activities. BetaAR antagonist ICI-118,551 and nonselective betaAR antagonists alprenolol, propranolol, and timolol produced negative chronotropic effects. In contrast, nonselective betaAR antagonists pindolol and nadolol as well as beta1AR-selective antagonists atenolol, acebutolol, and metoprolol did not cause a significant decrease in atrial rates. The neutral antagonist pindolol but not the inverse agonist alprenolol inhibited the negative chronotropic activities of ICI-118,551. Isoprenaline, salbutamol, and noradrenaline produced positive chronotropic effects; the chronotropic effects of isoprenaline and salbutamol but not of noradrenaline were antagonized by ICI-118,551. It is concluded that both beta1AR and beta2AR mediate positive chronotropic effects of catecholamines on rat and mouse atria but only beta2AR are constitutively active.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Nadolol	Beta-1 adrenergic receptor	Protein	Humans	Yes	Antagonist	Details