Biomaterial Database

Endogenous dopamine modifies electroresponsiveness of pars compacta cells in the guinea pig substantia nigra in vitro. 1989

R Kapoor, and C Webb, and S A Greenfield

University Department of Pharmacology, Oxford, U.K.

In the nigrostriatal pathway, dopamine is released not only from striatal nerve terminals, but also locally from the dendrites of nigrostriatal neurones within the substantia nigra itself. Exogenous dopamine is known to inhibit the firing of these neurones when applied directly to the substantia nigra in micromolar concentrations: but the amounts used are probably much higher than the endogenous concentration of the transmitter. Moreover, the direct, local blockade of nigral dopamine autoreceptors has not been reported to affect the firing rates of these neurones. The electrophysiological effects of endogenous dopamine were therefore examined using intracellular recordings from the substantia nigra in vitro. When slices of the midbrain were pharmacologically depleted of endogenous dopamine, selective membrane properties of nigrostriatal neurones were altered in a manner consistent with the effects of the exogenous transmitter. Similar changes were observed in control slices on exposure to the dopamine antagonist haloperidol. It is concluded that endogenous dopamine normally exerts a tonic influence on the electrical properties of nigrostriatal neurones.

UI	MeSH Term	Description	Entries
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D008781	Methyltyrosines	A group of compounds that are methyl derivatives of the amino acid TYROSINE.
D012110	Reserpine	An alkaloid found in the roots of Rauwolfia serpentina and R. vomitoria. Reserpine inhibits the uptake of norepinephrine into storage vesicles resulting in depletion of catecholamines and serotonin from central and peripheral axon terminals. It has been used as an antihypertensive and an antipsychotic as well as a research tool, but its adverse effects limit its clinical use.	Raunervil,Raupasil,Rausedil,Rausedyl,Serpasil,Serpivite,V-Serp,V Serp
D004298	Dopamine	One of the catecholamine NEUROTRANSMITTERS in the brain. It is derived from TYROSINE and is the precursor to NOREPINEPHRINE and EPINEPHRINE. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. A family of receptors (RECEPTORS, DOPAMINE) mediate its action.	Hydroxytyramine,3,4-Dihydroxyphenethylamine,4-(2-Aminoethyl)-1,2-benzenediol,Dopamine Hydrochloride,Intropin,3,4 Dihydroxyphenethylamine,Hydrochloride, Dopamine
D005260	Female		Females
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
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
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
D013378	Substantia Nigra	The black substance in the ventral midbrain or the nucleus of cells containing the black substance. These cells produce DOPAMINE, an important neurotransmitter in regulation of the sensorimotor system and mood. The dark colored MELANIN is a by-product of dopamine synthesis.	Nigra, Substantia,Nigras, Substantia,Substantia Nigras
D019805	alpha-Methyltyrosine	An inhibitor of the enzyme TYROSINE 3-MONOOXYGENASE, and consequently of the synthesis of catecholamines. It is used to control the symptoms of excessive sympathetic stimulation in patients with PHEOCHROMOCYTOMA. (Martindale, The Extra Pharmacopoeia, 30th ed)	alpha-Methyl-p-tyrosine,DL-Tyrosine, alpha-methyl-,Demser,Metirosine,Metyrosine,Racemetirosine,alpha-MPT,alpha-Methyl-para-tyrosine,alpha-Methyltyrosine Hydrochloride,alpha-Methyltyrosine, (+,-)-Isomer,alpha-Methyltyrosine, (D,L)-Isomer,alpha-Methyltyrosine, (L)-Isomer,Hydrochloride, alpha-Methyltyrosine,alpha MPT,alpha Methyl p tyrosine,alpha Methyl para tyrosine,alpha Methyltyrosine,alpha Methyltyrosine Hydrochloride,alpha-methyl- DL-Tyrosine