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Mechanism of the Antihypertensive Effect of Alpha2-Agonists

1985; Lippincott Williams & Wilkins; Volume: 7; Issue: Supplement Linguagem: Inglês

10.1097/00005344-198500078-00007

1533-4023

Richard A. Gillis, Philip J. Gatti, John A. Quest,

Eicosanoids and Hypertension Pharmacology

Drugs such as clonidine. methyldopa. guana-benz, guanfacine. and lofexidine have their primary site of antihypertensive action in the central nervous system (CNS) to activate alpha2-adrenergic receptors and lower arterial pressure. The most probable CNS site of action of these drugs is the medulla oblongata at a post-synaptic location. Current evidence indicates that within the medulla. the prototype drug, clonidinc. most likely acts at the lateral reticular nucleus. I his site is the most sensitive in terms of hypotension occurring alter microinjection of clonidinc. In addition, lesion of this nucleus abolishes the hypotensive effect of systemically administered clonidinc. Recently, a clonidine-displacing endogenous brain substance has been isolated and partially purified from calf brain. Know ledge of where clonidinc acts to lower blood pressure should help in assessing the role of an endogenous clonidine-displacing substance in CNS control of cardiovascular function