Document Detail

Studies on the effect of chronic oral administration of minoxidil and hydralazine on vascular function in spontaneously hypertensive rats.
MedLine Citation:
PMID:  7441494     Owner:  NLM     Status:  MEDLINE    
Minoxidil and hydralazine are related in chemical structure. Minoxidil is effective for the treatment of hypertensive emergencies. This drug lowers total peripheral resistance and has a direct vasodilator action, in vivo, its mechanism of action is unknown. The present study evaluated the effects of chronic oral administration of minoxidil and hydralazine on the contractile and passive physical properties of protal veins and small (0.4-0.6 mm outside diameter) mesenteric arteries from spontaneously hypertensive Okamoto-Aoki rats. Minoxidil or hydralazine was added to the drinking water of spontaneously hypertensive rats for 14 days. Blood pressure and heart rate were measured every second day. The contractile responses of mesenteric arteries and portal veins were measured in vitro. Minoxidil (0.3-10 mg/kg/day) produced a dose-related reduction in blood pressure. The in vitro sensitivity (ED50) and maximal contractile tension development of mesenteric arteries to norepinephrine, angiotensin, calcium chloride, potassium chloride and prostaglandins D2, E2, F2 alpha, B2 and A2 were not affected by chronic treatment of spontaneously hypertensive rats with minoxidil. In portal veins, minoxidil did not affect the ED50 or maximal tension development to any agonist. Minoxidil decreased the passive stiffness of portal veins. Hydralazine (1-100 mg/kg/day) decreased arterial pressure and depressed the maximal contractile tension and passive stiffness of both mesenteric arteries and portal veins. The data suggest that the antihypertensive action of minoxidil and hydralazine may not be related to a direct depressant action of the drugs on vascular smooth muscle function. It is possible that hydralazine and minoxidil, although somewhat similar in structure, may lower blood pressure by two different mechanisms. Alternatively, the action of these two drugs may be similar but reside in sites other than the vascular smooth muscles studied.
S Greeberg
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of pharmacology and experimental therapeutics     Volume:  215     ISSN:  0022-3565     ISO Abbreviation:  J. Pharmacol. Exp. Ther.     Publication Date:  1980 Nov 
Date Detail:
Created Date:  1981-02-26     Completed Date:  1981-02-26     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0376362     Medline TA:  J Pharmacol Exp Ther     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  279-86     Citation Subset:  IM    
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MeSH Terms
Administration, Oral
Blood Pressure / drug effects
Hydralazine / administration & dosage,  pharmacology*
Hypertension / drug therapy*,  physiopathology
Mesenteric Arteries / drug effects
Minoxidil / administration & dosage,  pharmacology*
Muscle, Smooth, Vascular / drug effects*
Portal Vein / drug effects
Pyrimidines / pharmacology*
Vasoconstriction / drug effects
Grant Support
Reg. No./Substance:
0/Pyrimidines; 38304-91-5/Minoxidil; 86-54-4/Hydralazine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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