Study of the contraction induced by norepinephrine and clonidine in the isolated guinea-pig ileum. 1991

C C Reis
Laboratory of Pharmacology, School of Pharmaceutical Sciences, UNESP, Araraquara, Brazil.

1. Norepinephrine (NE) and clonidine produce a phasic, dose-dependent contraction of the isolated guinea-pig terminal ileum. 2. The effect of NE was blocked by prazosin which produced a parallel rightward shift of the concentration-effect curve to NE, with a significant depression of maximum effects. 3. Yohimbine and indomethacin noncompetitively blocked, whereas practolol potentiated, the contractile effect of NE. 4. The contractile effect of clonidine was not antagonized by indomethacin or atropine. 5. These results suggest that the isolated guinea-pig terminal ileum has excitatory receptors sensitive to clonidine stimulation and excitatory alpha receptors sensitive to blockade by prazosin, and that the activation of the latter may be related to the activation of endogenous prostaglandin synthesis.

UI MeSH Term Description Entries
D007082 Ileum The distal and narrowest portion of the SMALL INTESTINE, between the JEJUNUM and the ILEOCECAL VALVE of the LARGE INTESTINE.
D007213 Indomethacin A non-steroidal anti-inflammatory agent (NSAID) that inhibits CYCLOOXYGENASE, which is necessary for the formation of PROSTAGLANDINS and other AUTACOIDS. It also inhibits the motility of POLYMORPHONUCLEAR LEUKOCYTES. Amuno,Indocid,Indocin,Indomet 140,Indometacin,Indomethacin Hydrochloride,Metindol,Osmosin
D008297 Male Males
D009119 Muscle Contraction A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments. Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009130 Muscle, Smooth Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed) Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
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
D011217 Practolol A beta-1 adrenergic antagonist that has been used in the emergency treatment of CARDIAC ARRYTHMIAS. Dalzic,Eralzdin Practolol,ICI-50172,ICI 50172,ICI50172,Practolol, Eralzdin
D011224 Prazosin A selective adrenergic alpha-1 antagonist used in the treatment of HEART FAILURE; HYPERTENSION; PHEOCHROMOCYTOMA; RAYNAUD DISEASE; PROSTATIC HYPERTROPHY; and URINARY RETENTION. Furazosin,Minipress,Pratsiol,Prazosin HCL,Prazosin Hydrochloride,HCL, Prazosin,Hydrochloride, Prazosin
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
D006168 Guinea Pigs A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research. Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea

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