1 The chronotropic effects of alpha- and beta-adrenoceptor agonists were investigated in the pithed rat. 2 The beta-adrenoceptor agonist, isoprenaline, produced only a positive chronotropic response. alpha 1-Adrenoceptor agonists, phenylephrine and amidephrine, produced positive and negative chronotropic effects. Part of the response to phenylephrine was beta-mediated. 3 A positive chronotropic response to amidephrine and phenylephrine was mediated directly through cardiac alpha 1-adrenoceptors and had a different time course from beta-adrenoceptor-mediated responses. 4 A negative chronotropic response to alpha-agonists was potentiated by neostigmine and blocked by atropine, tetrodotoxin or hexamethonium as well as by alpha 1-adrenoceptor antagonists. This may indicate alpha 1-adrenoceptors on preganglionic parasympathetic nerves, stimulation of these receptors causing release of acetylcholine. 5 The alpha 2-adrenoceptor agonist, xylazine, produced a direct negative chronotropic effect on the heart, independent of alpha-adrenoceptors. No evidence was found for functional post-junctional alpha 2-adrenoceptors. At high doses xylazine stimulated cardiac alpha 1-adrenoceptors.
Qualitative differences between beta-adrenergic and alpha-adrenergic inotropic effects in rat heart muscle
Comparison of pre-junctional alpha-adrenoceptors at the neuromuscular junction with vascular post-junctional alpha-receptors in cat skeletal muscle
An analysis of some factors influencing alpha-adrenoceptor feed-back at the sympathetic junction in the rat heart
Differentiation by cholinergic stimulation of positive inotropic actions mediated via alpha- and beta-adrenoceptors in the rabbit heart
Pre- and postsynaptic effects of yohimbine stereoisomers on noradrenergic transmission in the pulmonary artery of the rabbit
Effects of isoprenaline and phenylephrine on energy-rich phosphate compounds and glucose-6-phosphate in smooth and cardiac muscle
A method of stimulating different segments of the autonomic outflow from the spinal column to various organs in the pithed cat and rat
A comparison of pre- and post-junctional potencies of several alpha-adrenoceptor agonists in the cardiovascular system and anococcygeus muscle of the rat. Evidence for two types of post-junctional alpha-adrenoceptor
Postsynaptic alpha-adrenoceptor subtypes in rabbit blood vessels and rat anococcygeus muscle studied in vitro
The factors influencing the time course of drug action at alpha-adrenoceptors: an investigation of the effects of clonidine in the pithed rat
Thyroid-dependent alterations of myocardial adrenoceptors and adrenoceptor-mediated responses in the rat
Comparison of the effects of detomidine and xylazine on some alpha 2-adrenoceptor-mediated responses in the central and peripheral nervous systems.
Presynaptic interaction between vagal and sympathetic innervation in the heart: modulation of acetylcholine and noradrenaline release.
Involvement of alpha 1-adrenoceptors in chronotropic responses to endogenously released amines in the pithed rat
Pharmacological analysis of the cardiac effects of 5-HT and some 5-HT receptor agonists in the pithed rat.
Mechanisms contributing to the differential haemodynamic effects of bombesin and cholecystokinin in conscious, Long Evans rats
Mechanisms contributing to the regional haemodynamic effects of neurotensin in conscious, unrestrained Long Evans rats
An investigation of presynaptic alpha-adrenoceptor subtypes in the pithed rat heart and in the rat isolated vas deferens
Pharmacological analysis of hemodynamic responses to Lachesis muta (South American bushmaster) snake venom in anesthetized rats
Peripheral cardiovascular alpha- and beta-adrenergic effects of some hypotensive and bradycardic arylalkyl imidazole derivatives in the rat
Patterns of cardiovascular variability after long-term sino-aortic denervation in unanesthetized adult rats
Adrenergic Receptors: Trafficking
Adrenergic receptor trafficking is an active physiological process where adrenergic receptors are relocated from one region of the cell to another or from one type of cell to another. Discover the latest research on adrenergic receptor trafficking here.
Cardiac electrophysiology is the study of electrical activities of the heart and includes the assessment, diagnosis, and treatment of cardiac events. Find the latest research on cardiac electrophysiology here.