Regulation of noradrenaline release from rat occipital cortex tissue chops by alpha 2-adrenergic agonists. 1991

M L Ong, and S G Ball, and P F Vaughan
Department of Biochemistry, University of Glasgow, Scotland.

Noradrenaline (NA) and the alpha 2-adrenergic agonists clonidine, BHT-920, and UK 14304-18 inhibit potassium-evoked release of [3H]NA from rat occipital cortex tissue chops with similar potencies. NA (10(-5) M) was most effective as up to 85% inhibition could be observed compared with 75%, 55%, and 35% for UK 14304-18, clonidine, and BHT-920, respectively, all at 10(-5) M. Potassium-evoked release was enhanced by both forskolin (10(-5) M) and 1 mM dibutyryl cyclic AMP. Pretreatment of tissue chops with 1 mM dibutyryl cyclic AMP in the presence of 3-isobutyl-1-methylxanthine partially reversed the alpha 2-adrenergic agonist inhibition of NA release. No reversal of inhibition was observed following pretreatment with 10(-5) M forskolin. The effects of clonidine, BHT-920, UK-14308-18, and NA on cyclic AMP formation stimulated by (a) forskolin, (b) isoprenaline, (c) adenosine, (d) potassium, and (e) NA were examined. Only cAMP formation stimulated by NA was inhibited by these alpha 2-adrenergic agonists. These results suggest that only a small fraction of adenylate cyclase in rat occipital cortex is coupled to alpha 2-adrenergic receptors. These results are discussed in relation to recent findings that several alpha 2-adrenergic receptor subtypes occur, not all of which are coupled to the inhibition of adenylate cyclase, and that alpha 2-adrenergic receptors inhibit NA release in rat occipital cortex by a mechanism that does not involve decreasing cyclic AMP levels.

UI MeSH Term Description Entries
D008297 Male Males
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
D009778 Occipital Lobe Posterior portion of the CEREBRAL HEMISPHERES responsible for processing visual sensory information. It is located posterior to the parieto-occipital sulcus and extends to the preoccipital notch. Annectant Gyrus,Calcarine Fissure,Calcarine Sulcus,Cuneate Lobule,Cuneus,Cuneus Cortex,Cuneus Gyrus,Gyrus Lingualis,Lingual Gyrus,Lunate Sulcus,Medial Occipitotemporal Gyrus,Occipital Cortex,Occipital Gyrus,Occipital Region,Occipital Sulcus,Sulcus Calcarinus,Calcarine Fissures,Calcarinus, Sulcus,Cortex, Cuneus,Cortex, Occipital,Cortices, Cuneus,Cortices, Occipital,Cuneate Lobules,Cuneus Cortices,Fissure, Calcarine,Fissures, Calcarine,Gyrus Linguali,Gyrus, Annectant,Gyrus, Cuneus,Gyrus, Lingual,Gyrus, Medial Occipitotemporal,Gyrus, Occipital,Linguali, Gyrus,Lingualis, Gyrus,Lobe, Occipital,Lobes, Occipital,Lobule, Cuneate,Lobules, Cuneate,Occipital Cortices,Occipital Lobes,Occipital Regions,Occipitotemporal Gyrus, Medial,Region, Occipital,Regions, Occipital,Sulcus, Calcarine,Sulcus, Lunate,Sulcus, Occipital
D011810 Quinoxalines Quinoxaline
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
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
D003994 Bucladesine A cyclic nucleotide derivative that mimics the action of endogenous CYCLIC AMP and is capable of permeating the cell membrane. It has vasodilator properties and is used as a cardiac stimulant. (From Merck Index, 11th ed) Dibutyryl Adenosine-3',5'-Monophosphate,Dibutyryl Cyclic AMP,(But)(2) cAMP,Bucladesine, Barium (1:1) Salt,Bucladesine, Disodium Salt,Bucladesine, Monosodium Salt,Bucladesine, Sodium Salt,DBcAMP,Dibutyryl Adenosine 3,5 Monophosphate,N',O'-Dibutyryl-cAMP,N(6),0(2')-Dibutyryl Cyclic AMP,AMP, Dibutyryl Cyclic,Adenosine-3',5'-Monophosphate, Dibutyryl,Cyclic AMP, Dibutyryl,Dibutyryl Adenosine 3',5' Monophosphate,Disodium Salt Bucladesine,Monosodium Salt Bucladesine,N',O' Dibutyryl cAMP,Sodium Salt Bucladesine
D005576 Colforsin Potent activator of the adenylate cyclase system and the biosynthesis of cyclic AMP. From the plant COLEUS FORSKOHLII. Has antihypertensive, positive inotropic, platelet aggregation inhibitory, and smooth muscle relaxant activities; also lowers intraocular pressure and promotes release of hormones from the pituitary gland. Coleonol,Forskolin,N,N-Dimethyl-beta-alanine-5-(acetyloxy)-3-ethenyldodecahydro-10,10b-dihydroxy-3,4a,7,7,10a-pentamethyl-1-oxo-1H-naphtho(2,1-b)pyran-6-yl Ester HCl,NKH 477,NKH-477,NKH477
D006652 Histological Techniques Methods of preparing tissue for examination and study of the origin, structure, function, or pathology. Histologic Technic,Histologic Technics,Histologic Technique,Histologic Techniques,Histological Technics,Technic, Histologic,Technics, Histologic,Technique, Histologic,Techniques, Histologic,Histological Technic,Histological Technique,Technic, Histological,Technics, Histological,Technique, Histological,Techniques, Histological
D000068438 Brimonidine Tartrate A quinoxaline derivative and ADRENERGIC ALHPA-2 RECEPTOR AGONIST that is used to manage INTRAOCULAR PRESSURE associated with OPEN-ANGLE GLAUCOMA and OCULAR HYPERTENSION. 5-Bromo-6-(2-imidazolin-2-ylamino)quinoxaline D-tartrate,5-bromo-6-(imidazolidinylideneamino)quinoxaline,5-bromo-6-(imidazolin-2-ylamino)quinoxaline,AGN 190342,AGN-190342,Alphagan,Alphagan P,Brimonidine,Brimonidine Purite,Brimonidine Tartrate (1:1),Brimonidine Tartrate (1:1), (S-(R*,R*))-Isomer,Brimonidine Tartrate, (R-(R*,R*))-Isomer,Bromoxidine,Mirvaso,Ratio-Brimonidine,Sanrosa,UK 14,304,UK 14,304-18,UK 14304,UK 14308,UK-14,304-18,UK-14,308,UK-14304,AGN190342,Ratio Brimonidine,UK 14,304 18,UK 14,30418,UK 14,308,UK14,30418,UK14,308,UK14304

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