Positive chronotropic and inotropic responses to release of norepinephrine from sympathetic nerve terminals produced by nitroglycerin in atria. 1991

S X Ma, and J P Long
Department of Pharmacology, College of Medicine, University of Iowa, Iowa City 52242.

Nitroglycerin produced concentration-dependent increases in spontaneous rate and enhancements of positive chronotropic and inotropic responses to transmural stimulation of isolated right guinea-pig atria. The effects of nitroglycerin were significantly potentiated by desmethylimipramine, which is an inhibitor of norepinephrine uptake, and were significantly inhibited by either guanethidine, which inhibits release of norepinephrine, or alpha-methyl-p-tyrosine, which inhibits synthesis of norepinephrine. The effects of nitroglycerin were not modified by either prazosin or atropine, but were significantly inhibited by either the beta-adrenoceptor antagonist propranolol or the alpha 2-adrenoceptor antagonist yohimbine. Nitroglycerin significantly increased the concentration of norepinephrine in the medium bathing atria and the 3,4-dihydroxyphenylglycol concentration in the atrial tissue, which were quantified using high-performance liquid chromatography with electrochemical detection. The atrial responses to nitroglycerin appear to mimic sympathetic neuronal activities and may involve the modulatory role of alpha 2-adrenoceptors in the release of norepinephrine.

UI MeSH Term Description Entries
D008734 Methoxyhydroxyphenylglycol Synthesized from endogenous epinephrine and norepinephrine in vivo. It is found in brain, blood, CSF, and urine, where its concentrations are used to measure catecholamine turnover. Hydroxymethoxyphenylglycol,MHPG,MOPEG,Vanylglycol,4-Hydroxy-3-methoxyphenylethylene Glycol,4-Hydroxy-3-methoxyphenylethyleneglycol,4-Hydroxy-3-methoxyphenylglycol,Methoxyhydroxyphenylglycol, (+)-Isomer,Methoxyhydroxyphenylglycol, (+-)-Isomer,Methoxyhydroxyphenylglycol, (-)-Isomer,4 Hydroxy 3 methoxyphenylethylene Glycol,4 Hydroxy 3 methoxyphenylethyleneglycol,4 Hydroxy 3 methoxyphenylglycol
D009200 Myocardial Contraction Contractile activity of the MYOCARDIUM. Heart Contractility,Inotropism, Cardiac,Cardiac Inotropism,Cardiac Inotropisms,Contractilities, Heart,Contractility, Heart,Contraction, Myocardial,Contractions, Myocardial,Heart Contractilities,Inotropisms, Cardiac,Myocardial Contractions
D009206 Myocardium The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow. Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D009411 Nerve Endings Branch-like terminations of NERVE FIBERS, sensory or motor NEURONS. Endings of sensory neurons are the beginnings of afferent pathway to the CENTRAL NERVOUS SYSTEM. Endings of motor neurons are the terminals of axons at the muscle cells. Nerve endings which release neurotransmitters are called PRESYNAPTIC TERMINALS. Ending, Nerve,Endings, Nerve,Nerve Ending
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
D005996 Nitroglycerin A volatile vasodilator which relieves ANGINA PECTORIS by stimulating GUANYLATE CYCLASE and lowering cytosolic calcium. It is also sometimes used for TOCOLYSIS and explosives. Glyceryl Trinitrate,Anginine,Dynamite,Gilustenon,Nitrangin,Nitro-Bid,Nitro-Dur,Nitrocard,Nitroderm,Nitroderm TTS,Nitroglyn,Nitrol,Nitrolan,Nitrong,Nitrospan,Nitrostat,Perlinganit,Susadrin,Sustac,Sustak,Sustonit,Transderm Nitro,Tridil,Trinitrin,Trinitrolong,Nitro Bid,Nitro Dur,NitroBid,NitroDur,Trinitrate, Glyceryl
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
D006321 Heart The hollow, muscular organ that maintains the circulation of the blood. Hearts
D006325 Heart Atria The chambers of the heart, to which the BLOOD returns from the circulation. Heart Atrium,Left Atrium,Right Atrium,Atria, Heart,Atrium, Heart,Atrium, Left,Atrium, Right
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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