Related Experiment Video
Updated: Aug 17, 2026

Bladder Smooth Muscle Strip Contractility as a Method to Evaluate Lower Urinary Tract Pharmacology
Published on: August 18, 2014
COMPARISON OF THE EFFECTS OF BRETYLIUM, GUANETHIDINE AND BETHANIDINE ON SMOOTH MUSCLE RESPONSES TO DIFFERENT RATES OF
Abstract:
The relative effects of bretylium, guanethidine and bethanidine on smooth muscle responses to different rates of sympathetic nerve stimulation have been compared. The responses studied were vasoconstriction in the femoral vascular bed and contraction of the spleen in anaesthetized cats, vasoconstriction in perfused ears of rabbits and inhibition of pendular movements in rabbit isolated ileum preparations. Except in the isolated ileum, the action of bretylium on curves relating the frequency of nerve stimulation and the effect on response was different from that of guanethidine. Whereas bretylium caused relatively greater inhibition of responses to high stimulus frequencies and depressed the slopes of the curves, guanethidine preferentially suppressed responses to low stimulus frequencies and caused roughly parallel shifts of the curves. In each situation tested bethanidine was the most potent of the three blocking agents and in general its effect on frequency/response curves was intermediate between those of bretylium and guanethidine.
More Related Videos
06:30Quantifying Acute Changes in Renal Sympathetic Nerve Activity in Response to Central Nervous System Manipulations in Anesthetized Rats
Published on: September 11, 2018
08:41Assessment of Vascular Tone Responsiveness using Isolated Mesenteric Arteries with a Focus on Modulation by Perivascular Adipose Tissues
Published on: June 3, 2019
Related Concept Videos
Direct-Acting Cholinergic Agonists: Pharmacological Actions
Drugs Acting on Autonomic Ganglia: Blockers
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 Agonists: Direct-Acting Agents
These agents can be classified...
Antihypertensive Drugs: Vasodilators
Heart Failure Drugs: β-Blockers