Biomaterial Database

Alpha-1 and alpha-2 adrenoceptor: response coupling in canine saphenous and femoral veins. 1986

N A Flavahan, and P M Vanhoutte

The aim of the present study was to analyze alpha-1 and alpha-2 adrenoceptor response coupling in isolated canine blood vessels. Rings of saphenous and femoral veins and of femoral arteries were suspended for isometric tension recording in modified Krebs-Ringer bicarbonate solution, gassed with 95% O2-5% CO2 and maintained at 37 degrees C. Dissociation constants for the alpha-1 adrenergic agonists, phenylephrine and cirazoline, and the alpha-2 adrenergic agonist, UK 14,304, were determined by analysis of concentration-effect curves to the agonists under control conditions and after partial inactivation of alpha adrenoceptors by phenoxybenzamine. The dissociation constant of phenylephrine for alpha-1 adrenoceptors in saphenous veins was approximately 10-fold higher than that obtained for the agonist in femoral arteries or femoral veins. Similarly the dissociation constant for cirazoline in the saphenous vein was higher than that obtained in other alpha-1 adrenergic systems. Dissociation constants were used to determine alpha adrenoceptor occupancy-response relationships. The alpha-1 adrenergic responses evoked by high intrinsic-efficacy agonists (cirazoline and phenylephrine) were associated with a very large receptor-reserve in the saphenous vein, but no, or only a limited receptor-reserve in the femoral vein. The dissociation constant for UK 14,304 in saphenous veins was significantly lower than that obtained for alpha-2 adrenergic stimulation by norepinephrine. There was no alpha-2 adrenoceptor reserve in the saphenous vein for these putative high intrinsic-efficacy agonists. The differences in receptor-reserve between alpha-1 adrenoceptors in canine saphenous and femoral veins and between alpha-1 and alpha-2 adrenoceptors in saphenous veins may help to explain the differential modulation of adrenergic responses in these blood vessels.

UI	MeSH Term	Description	Entries
D007093	Imidazoles	Compounds containing 1,3-diazole, a five membered aromatic ring containing two nitrogen atoms separated by one of the carbons. Chemically reduced ones include IMIDAZOLINES and IMIDAZOLIDINES. Distinguish from 1,2-diazole (PYRAZOLES).
D008297	Male		Males
D008433	Mathematics	The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Mathematic
D009638	Norepinephrine	Precursor of epinephrine that is secreted by the ADRENAL MEDULLA and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the LOCUS CERULEUS. It is also found in plants and is used pharmacologically as a sympathomimetic.	Levarterenol,Levonorepinephrine,Noradrenaline,Arterenol,Levonor,Levophed,Levophed Bitartrate,Noradrenaline Bitartrate,Noradrénaline tartrate renaudin,Norepinephrin d-Tartrate (1:1),Norepinephrine Bitartrate,Norepinephrine Hydrochloride,Norepinephrine Hydrochloride, (+)-Isomer,Norepinephrine Hydrochloride, (+,-)-Isomer,Norepinephrine d-Tartrate (1:1),Norepinephrine l-Tartrate (1:1),Norepinephrine l-Tartrate (1:1), (+,-)-Isomer,Norepinephrine l-Tartrate (1:1), Monohydrate,Norepinephrine l-Tartrate (1:1), Monohydrate, (+)-Isomer,Norepinephrine l-Tartrate (1:2),Norepinephrine l-Tartrate, (+)-Isomer,Norepinephrine, (+)-Isomer,Norepinephrine, (+,-)-Isomer
D010643	Phenoxybenzamine	An alpha-adrenergic antagonist with long duration of action. It has been used to treat hypertension and as a peripheral vasodilator.	Dibenylene,Dibenyline,Dibenziran,Dibenzylin,Dibenzyline,Dibenzyran,Phenoxybenzamine Hydrochloride,Hydrochloride, Phenoxybenzamine
D010656	Phenylephrine	An alpha-1 adrenergic agonist used as a mydriatic, nasal decongestant, and cardiotonic agent.	(R)-3-Hydroxy-alpha-((methylamino)methyl)benzenemethanol,Metaoxedrin,Metasympatol,Mezaton,Neo-Synephrine,Neosynephrine,Phenylephrine Hydrochloride,Phenylephrine Tannate,Neo Synephrine,Tannate, Phenylephrine
D011810	Quinoxalines		Quinoxaline
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
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
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response