|In summary: satellite symposium on central alpha-adrenergic blood pressure regulating mechanisms.|
|PMID: 6150004 Owner: NLM Status: MEDLINE|
|This symposium reviewed the fundamental principles, pharmacology, and clinical pharmacology of central alpha-adrenergic blood pressure regulating mechanisms. Fundamental principles Arterial baro- and chemoreceptor signals reach the nucleus of the tractus solitarius (NTS) via vagal and glossopharyngeal afferents. The NTS communicates with sympathetic preganglionic neurons in the spinal cord via centers and tracts in the medulla, pons, and hypothalamus that include an alpha-adrenergic inhibitory network. Descending tracts emphasized in this symposium originate in the C-1 epinephrine cells of the medulla, B-1 and B-3 serotonin cells of the medulla, and A-5 norepinephrine cells of the pons. Transmitters involved are norepinephrine, epinephrine, serotonin, glutamate, and gamma-aminobutyric acid (GABA). Catecholamine enzymes share protein domains in their primary structures and may be coded by linked or single genes. New methods of purifying and locating alpha- and beta-receptors have been developed. Pharmacology Methyldopa, clonidine, and clonidine-like drugs lower blood pressure by stimulating postsynaptic alpha 2-receptors in a brain stem inhibitory network, which down-regulates these receptors. Alpha 1-receptors were found to be higher in normotensive than in hypertensive rats and were increased in the latter by methyldopa administration. Alpha 2-receptors were found to differ in various tissues, which permits the development of highly selective agonists and antagonists. Although alpha-methylnorepinephrine is probably the principal metabolite of methyldopa, alpha-methylepinephrine and alpha-methyldopamine may also contribute. The site of action usually is identified as the NTS. Possible roles for the descending tracts were suggested. Clinical pharmacology Methyldopa, clonidine, guanfacine, and related drugs lower blood pressure principally by CNS mechanisms but peripheral actions may also contribute.(ABSTRACT TRUNCATED AT 250 WORDS)|
|W B Abrams|
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|Type: Journal Article; Review|
|Title: Hypertension Volume: 6 ISSN: 0194-911X ISO Abbreviation: Hypertension Publication Date: 1984 Sep-Oct|
|Created Date: 1984-12-28 Completed Date: 1984-12-28 Revised Date: 2004-11-17|
Medline Journal Info:
|Nlm Unique ID: 7906255 Medline TA: Hypertension Country: UNITED STATES|
|Languages: eng Pagination: II87-93 Citation Subset: IM|
|APA/MLA Format Download EndNote Download BibTex|
Antihypertensive Agents / adverse effects
Blood Pressure* / drug effects
Brain / physiology
Clonidine / pharmacology
Epinephrine / physiology
Glossopharyngeal Nerve / physiology
Glutamates / physiology
Guanidines / pharmacology
Hypothalamus / physiology
Medulla Oblongata / physiology
Methyldopa / metabolism, pharmacology
Norepinephrine / metabolism, physiology
Phenylacetates / pharmacology
Pons / physiology
Pressoreceptors / physiology
Receptors, Adrenergic, alpha / physiology*
Serotonin / physiology
Spinal Cord / physiology
Substance Withdrawal Syndrome
Vagus Nerve / physiology
gamma-Aminobutyric Acid / physiology
|0/Antihypertensive Agents; 0/Glutamates; 0/Guanidines; 0/Phenylacetates; 0/Receptors, Adrenergic, alpha; 29110-47-2/Guanfacine; 4205-90-7/Clonidine; 50-67-9/Serotonin; 51-41-2/Norepinephrine; 51-43-4/Epinephrine; 555-30-6/Methyldopa; 56-12-2/gamma-Aminobutyric Acid; 56-86-0/Glutamic Acid|
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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