Mechanism of the depressor action of LY171555, a selective dopamine D2 receptor agonist, in the anesthetized rat. 1986

S Nagahama, and Y F Chen, and M D Lindheimer, and S Oparil

Administration of LY171555 (1 mg/kg i.v.) decreased mean arterial pressure (MAP) and heart rate in both pentobarbital- and urethane-anesthesized Sprague-Dawley rats. The depressor response to LY171555 in pentobarbital-anesthetized rats was sustained for at least 30 min, but in urethane-anesthetized rats lasted only approximately 3 min after LY171555 injection. In pentobarbital-anesthetized rats, pretreatment with domperidone (0.5 mg/kg) or metoclopramide (5 mg/kg) attenuated the depressor action of LY171555, whereas pretreatment with d(CH2)5Tyr(Me)arginine vasopressin (AVP) (10 micrograms/kg) only delayed the recovery phase of the depressor response to LY171555. In contrast, LY171555 administered to urethane-anesthetized rats after domperidone pretreatment induced a pressor response which was blocked completely by d(CH2)5Tyr(Me)AVP. Metoclopramide pretreatment in urethane-anesthetized rats prevented the decreases in MAP and heart rate induced by LY171555, whereas pretreatment with d(CH2)5Tyr(Me)AVP delayed the recovery phase of the depressor response. Pretreatment with d(CH2)5Tyr(Me)AVP per se decreased basal MAP in the urethane-anesthetized group, but not in pentobarbital-anesthetized rats. Basal plasma norepinephrine, epinephrine and AVP levels were higher in urethane-anesthetized rats than in the pentobarbital-anesthetized group. LY171555 administration decreased plasma norepinephrine without altering plasma epinephrine in both groups and induced a significant increase in plasma AVP which was greater in the urethane-anesthetized rats than in pentobarbital-anesthetized animals. These results suggest that LY171555 decreases MAP and heart rate in anesthetized rats by inhibiting norepinephrine release from nerve endings through the peripheral dopamine D2 receptor and that the time course of the depressor response may be altered by LY171555-induced AVP release, the magnitude of which appears to be dependent on the anesthetic agent.

UI MeSH Term Description Entries
D008787 Metoclopramide A dopamine D2 antagonist that is used as an antiemetic. 4-Amino-5-chloro-N-(2-(diethylamino)ethyl)-2-methoxybenzamide,Cerucal,Maxolon,Metaclopramide,Metoclopramide Dihydrochloride,Metoclopramide Hydrochloride,Metoclopramide Monohydrochloride,Metoclopramide Monohydrochloride, Monohydrate,Primperan,Reglan,Rimetin,Dihydrochloride, Metoclopramide,Hydrochloride, Metoclopramide,Monohydrochloride, Metoclopramide
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
D010424 Pentobarbital A short-acting barbiturate that is effective as a sedative and hypnotic (but not as an anti-anxiety) agent and is usually given orally. It is prescribed more frequently for sleep induction than for sedation but, like similar agents, may lose its effectiveness by the second week of continued administration. (From AMA Drug Evaluations Annual, 1994, p236) Mebubarbital,Mebumal,Diabutal,Etaminal,Ethaminal,Nembutal,Pentobarbital Sodium,Pentobarbital, Monosodium Salt,Pentobarbitone,Sagatal,Monosodium Salt Pentobarbital
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
D001794 Blood Pressure PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS. Systolic Pressure,Diastolic Pressure,Pulse Pressure,Pressure, Blood,Pressure, Diastolic,Pressure, Pulse,Pressure, Systolic,Pressures, Systolic
D004294 Domperidone A specific blocker of dopamine receptors. It speeds gastrointestinal peristalsis, causes prolactin release, and is used as antiemetic and tool in the study of dopaminergic mechanisms. Apo-Domperidone,Domidon,Domperidon,Domperidon AL,Domperidon Hexal,Domperidon Stada,Domperidon-TEVA,Domperidona Gamir,Domperidone Maleate,Domperidone Maleate (1:1),Domperidone Monohydrochloride,Gastrocure,Motilium,Nauzelin,Novo-Domperidone,Nu-Domperidone,PMS-Domperidone,Péridys,R-33,812,R-33812,Ratio-Domperidone,Apo Domperidone,Domperidon TEVA,Gamir, Domperidona,Hexal, Domperidon,Maleate, Domperidone,Monohydrochloride, Domperidone,Novo Domperidone,Nu Domperidone,PMS Domperidone,R33,812,R33812,Ratio Domperidone,Stada, Domperidon
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
D004837 Epinephrine The active sympathomimetic hormone from the ADRENAL MEDULLA. It stimulates both the alpha- and beta- adrenergic systems, causes systemic VASOCONSTRICTION and gastrointestinal relaxation, stimulates the HEART, and dilates BRONCHI and cerebral vessels. It is used in ASTHMA and CARDIAC FAILURE and to delay absorption of local ANESTHETICS. Adrenaline,4-(1-Hydroxy-2-(methylamino)ethyl)-1,2-benzenediol,Adrenaline Acid Tartrate,Adrenaline Bitartrate,Adrenaline Hydrochloride,Epifrin,Epinephrine Acetate,Epinephrine Bitartrate,Epinephrine Hydrochloride,Epinephrine Hydrogen Tartrate,Epitrate,Lyophrin,Medihaler-Epi,Acetate, Epinephrine
D004873 Ergolines A series of structurally-related alkaloids that contain the ergoline backbone structure. Ergoline
D006339 Heart Rate The number of times the HEART VENTRICLES contract per unit of time, usually per minute. Cardiac Rate,Chronotropism, Cardiac,Heart Rate Control,Heartbeat,Pulse Rate,Cardiac Chronotropy,Cardiac Chronotropism,Cardiac Rates,Chronotropy, Cardiac,Control, Heart Rate,Heart Rates,Heartbeats,Pulse Rates,Rate Control, Heart,Rate, Cardiac,Rate, Heart,Rate, Pulse

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