Biomaterial Database

Effects of several catecholamines on sympathetic transmission to the myocardium: role of presynaptic alpha-adrenoceptors. 1977

M F Lokhandwala, and J T Coats, and J P Buckley

Effects of several alpha-adrenoceptor agonists on presynaptic alpha-adrenoceptors were evaluated by studying chronotropic responses to cardioaccelerator nerve stimulation in anesthetized dogs. I.v. infusions of norepinephrine (NE), methylnorepinephrine (MNE), epinephrine (E) or phenylephrine (PHE) in desipramine-treated dogs caused significant attenuation of nerve stimulation responses. The inhibitory influence of all these agents could be prevented by prior treatment with phentolamine, but not with haloperidol. Comparisons of relative pressor and presynaptic inhibitory actions of these compounds revealed that in equipressor doses, MNE caused a significantly greater attenuation of nerve stimmulation responses than NE, while PHE had similar pressor and presynaptic inhibitory activity to that of NE. The inhibition of chronotropic responses to nerve stimulation observed following E was significantly greater compared to its relative pressor effect. These results demonstrate the existence of a presynaptic alpha-adrenoceptor mechanism modulating cardiac rate in intact dogs and indicate that the false transmitter MNE may be more potent than NE in imparing neuronal transmission by an action on presynaptic alpha-adrenoceptors.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009435	Synaptic Transmission	The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES.	Neural Transmission,Neurotransmission,Transmission, Neural,Transmission, Synaptic
D010646	Phentolamine	A nonselective alpha-adrenergic antagonist. It is used in the treatment of hypertension and hypertensive emergencies, pheochromocytoma, vasospasm of RAYNAUD DISEASE and frostbite, clonidine withdrawal syndrome, impotence, and peripheral vascular disease.	Fentolamin,Phentolamine Mesilate,Phentolamine Mesylate,Phentolamine Methanesulfonate,Phentolamine Mono-hydrochloride,Regitine,Regityn,Rogitine,Z-Max,Mesilate, Phentolamine,Mesylate, Phentolamine,Methanesulfonate, Phentolamine,Mono-hydrochloride, Phentolamine,Phentolamine Mono hydrochloride
D011941	Receptors, Adrenergic	Cell-surface proteins that bind epinephrine and/or norepinephrine with high affinity and trigger intracellular changes. The two major classes of adrenergic receptors, alpha and beta, were originally discriminated based on their cellular actions but now are distinguished by their relative affinity for characteristic synthetic ligands. Adrenergic receptors may also be classified according to the subtypes of G-proteins with which they bind; this scheme does not respect the alpha-beta distinction.	Adrenergic Receptors,Adrenoceptor,Adrenoceptors,Norepinephrine Receptor,Receptors, Epinephrine,Receptors, Norepinephrine,Adrenergic Receptor,Epinephrine Receptors,Norepinephrine Receptors,Receptor, Adrenergic,Receptor, Norepinephrine
D011942	Receptors, Adrenergic, alpha	One of the two major pharmacological subdivisions of adrenergic receptors that were originally defined by the relative potencies of various adrenergic compounds. The alpha receptors were initially described as excitatory receptors that post-junctionally stimulate SMOOTH MUSCLE contraction. However, further analysis has revealed a more complex picture involving several alpha receptor subtypes and their involvement in feedback regulation.	Adrenergic alpha-Receptor,Adrenergic alpha-Receptors,Receptors, alpha-Adrenergic,alpha-Adrenergic Receptor,alpha-Adrenergic Receptors,Receptor, Adrenergic, alpha,Adrenergic alpha Receptor,Adrenergic alpha Receptors,Receptor, alpha-Adrenergic,Receptors, alpha Adrenergic,alpha Adrenergic Receptor,alpha Adrenergic Receptors,alpha-Receptor, Adrenergic,alpha-Receptors, Adrenergic
D002395	Catecholamines	A general class of ortho-dihydroxyphenylalkylamines derived from TYROSINE.	Catecholamine,Sympathin,Sympathins
D003891	Desipramine	A tricyclic dibenzazepine compound that potentiates neurotransmission. Desipramine selectively blocks reuptake of norepinephrine from the neural synapse, and also appears to impair serotonin transport. This compound also possesses minor anticholinergic activity, through its affinity to muscarinic receptors.	Desmethylimipramine,Apo-Desipramine,Demethylimipramine,Desipramine Hydrochloride,Norpramin,Novo-Desipramine,Nu-Desipramine,PMS-Desipramine,Pertofran,Pertofrane,Pertrofran,Petylyl,Ratio-Desipramine,Apo Desipramine,Hydrochloride, Desipramine,Novo Desipramine,Nu Desipramine,PMS Desipramine,Ratio Desipramine
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog
D004347	Drug Interactions	The action of a drug that may affect the activity, metabolism, or toxicity of another drug.	Drug Interaction,Interaction, Drug,Interactions, Drug
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical