Pharmacological evidence for high affinity and low affinity a2-adrenoceptor binding sites in rat vas deferens. 1983

D R Mottram

Differential antagonistic activity against imidazoline- and phenethylamine-induced inhibition of field stimulated rat vas deferens is described. Competitive antagonism of the imidazolines, chlonidine and B-HT 920, was produced by the a2-selective antagonists yohimbine and phentolamine, whereas, only partial antagonism of a-methyl noradrenaline and adrenaline was observed. Higher concentrations of yohimbine (above 2 microM) and phentolamine (above 20 microM) failed to produce a further shift in the dose-response curves of these agonists. The rate of recovery of the twitch response following clonidine- or B-HT 920-induced inhibition was very slow, even after repeated washing of the tissue. On the other hand recovery following a-methyl noradrenaline or adrenaline was extremely rapid. The present results provide pharmacological evidence in support of the previously proposed existence of high and low affinity binding site on the a2-adrenoceptor.

UI MeSH Term Description Entries
D008297 Male Males
D008771 Nordefrin A norepinephrine derivative used as a vasoconstrictor agent. Methylnorepinephrine,3,4-Dihydroxynorephedrine,4-(2-Amino-1-hydroxypropyl)-1,2-benzenediol,4-(2-Amino-1-hydroxypropyl)-1,2-benzenediol Hydrochloride, (R*,R*)-(+,-)-Isomer,4-(2-Amino-1-hydroxypropyl)-1,2-benzenediol Hydrochloride, (R*,S*)-(+-)-Isomer,4-(2-Amino-1-hydroxypropyl)-1,2-benzenediol Tartrate, (R*,R*), (R*,R*)-Isomer,4-(2-Amino-1-hydroxypropyl)-1,2-benzenediol Tartrate, (R*,S*), (R*,R*)-Isomer,4-(2-Amino-1-hydroxypropyl)-1,2-benzenediol, (R*,R*)-Isomer,4-(2-Amino-1-hydroxypropyl)-1,2-benzenediol, (R*,S*)-Isomer,Cobefrine,Corbadrine,Levonordefrin,Neo-Cobefrin,Nordefrin Hydrochloride,Nordefrin Hydrochloride, (R*,R*)-(+,-)-Isomer,Nordefrin Hydrochloride, (R*,S*)-(+,-)-Isomer,Nordefrin Tartrate, (R*,R*), (R*,R*) Isomer,Nordefrin Tartrate, (R*,S*), (R*,R*) Isomer,Nordefrin, (R*,R*)-Isomer,Nordefrin, (R*,S*)-Isomer,Norephrine,alpha-Methylnoradrenaline,alpha-Methylnorepinephrine,3,4 Dihydroxynorephedrine,Hydrochloride, Nordefrin,Neo Cobefrin,NeoCobefrin,alpha Methylnoradrenaline,alpha Methylnorepinephrine
D011919 Rats, Inbred Strains Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding. August Rats,Inbred Rat Strains,Inbred Strain of Rat,Inbred Strain of Rats,Inbred Strains of Rats,Rat, Inbred Strain,August Rat,Inbred Rat Strain,Inbred Strain Rat,Inbred Strain Rats,Inbred Strains Rat,Inbred Strains Rats,Rat Inbred Strain,Rat Inbred Strains,Rat Strain, Inbred,Rat Strains, Inbred,Rat, August,Rat, Inbred Strains,Rats Inbred Strain,Rats Inbred Strains,Rats, August,Rats, Inbred Strain,Strain Rat, Inbred,Strain Rats, Inbred,Strain, Inbred Rat,Strains, Inbred Rat
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
D003000 Clonidine An imidazoline sympatholytic agent that stimulates ALPHA-2 ADRENERGIC RECEPTORS and central IMIDAZOLINE RECEPTORS. It is commonly used in the management of HYPERTENSION. Catapres,Catapresan,Catapressan,Chlophazolin,Clofelin,Clofenil,Clonidine Dihydrochloride,Clonidine Hydrochloride,Clonidine Monohydrobromide,Clonidine Monohydrochloride,Clopheline,Dixarit,Gemiton,Hemiton,Isoglaucon,Klofelin,Klofenil,M-5041T,ST-155,Dihydrochloride, Clonidine,Hydrochloride, Clonidine,M 5041T,M5041T,Monohydrobromide, Clonidine,Monohydrochloride, Clonidine,ST 155,ST155
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
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D014649 Vas Deferens The excretory duct of the testes that carries SPERMATOZOA. It rises from the SCROTUM and joins the SEMINAL VESICLES to form the ejaculatory duct. Ductus Deferens,Deferens, Ductus,Deferens, Vas
D015016 Yohimbine A plant alkaloid with alpha-2-adrenergic blocking activity. Yohimbine has been used as a mydriatic and in the treatment of ERECTILE DYSFUNCTION. Rauwolscine,Aphrodine Hydrochloride,Aphrodyne,Corynanthine,Corynanthine Tartrate,Pluriviron,Rauhimbine,Yocon,Yohimbin Spiegel,Yohimbine Houdé,Yohimbine Hydrochloride,Yohimex,Hydrochloride, Aphrodine,Hydrochloride, Yohimbine,Tartrate, Corynanthine
D051381 Rats The common name for the genus Rattus. Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus

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