Related Experiment Video
Updated: Oct 14, 2026

Disrupting Reconsolidation of Fear Memory in Humans by a Noradrenergic β-Blocker
Published on: December 18, 2014
Cardiac responsiveness after acute withdrawal of chronic propranolol treatment in rats
Abstract:
1. This study examined possible effects of chronic beta-adrenergic blockade on (a) rat myocardial beta-adrenergic receptors and (b) the responsiveness of isolated atria and right ventricular strips to various agents. 2. Following withdrawal of propranolol or saline treatment, significant left shifts were noted in the inotropic responses of propranolol-treated right ventricular strips to isoproterenol and norepinephrine. 3. This supersensitivity could not be demonstrated in left atrial inotropic or right atrial chronotropic responses. 4. Treatment and withdrawal did not alter (a) the inotropic responsiveness of right ventricular strips to extracellular calcium, methoxamine, ouabain, glucagon, 3-isobutyl-l-methylxanthine, acetylcholine or methacholine, or (b) beta-adrenergic receptors in ventricular membranes.
Related Concept Videos
Adrenergic Receptors: β Subtype
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...
Adrenergic Antagonists: Pharmacological Actions of β-Receptor Blockers
Antihypertensive Drugs: Action of β1 Blockers
Antihypertensive Drugs: Types of β-Blockers
Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers
Heart Failure Drugs: β-Blockers

