Nitric Oxide-Dependent Vasodilation in Young Spontaneously Hypertensive Rats

Conflicting evidence exists on the possible impairment of tonic nitric oxide (NO)-mediated vasodilation as a causative factor in the genesis of human as well as experimental hypertension. We evaluated the tonic NO-dependent vasodilation from the pressor response to NO synthesis inhibition by N (L-NM...

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Bibliographic Details
Published in:Hypertension (Dallas, Tex. 1979) Tex. 1979), 1998-10, Vol.32 (4), p.735-739
Main Authors: Radaelli, Alberto, Mircoli, Luca, Mori, Ileana, Mancia, Giuseppe, Ferrari, Alberto U
Format: Article
Language:English
Subjects:
Aging - physiology
Animals
Antihypertensive Agents - therapeutic use
Arterial hypertension. Arterial hypotension
Biological and medical sciences
Blood and lymphatic vessels
Blood Pressure - drug effects
Cardiology. Vascular system
Drug Interactions
Enzyme Inhibitors - pharmacology
Experimental diseases
Hexamethonium - therapeutic use
Hypertension - drug therapy
Hypertension - genetics
Hypertension - physiopathology
Infusions, Intravenous
Medical sciences
Nitric Oxide - antagonists & inhibitors
Nitric Oxide - physiology
omega-N-Methylarginine - pharmacology
Pressoreceptors - drug effects
Rats
Rats, Inbred SHR
Rats, Inbred WKY
Species Specificity
Vasoconstrictor Agents - pharmacology
Vasodilation - drug effects
Vasopressins - pharmacology
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Summary:Conflicting evidence exists on the possible impairment of tonic nitric oxide (NO)-mediated vasodilation as a causative factor in the genesis of human as well as experimental hypertension. We evaluated the tonic NO-dependent vasodilation from the pressor response to NO synthesis inhibition by N (L-NMMA) in 9 conscious, chronically instrumented spontaneously hypertensive rats (SHR) at 12 weeks of age, ie, during the early established hypertensive stage. Nine age-matched Wistar-Kyoto rats (WKY) were used as controls. The pressor responses to L-NMMA (100 mg [middle dot] kg IV bolus plus 1.5 mg [middle dot] kg [middle dot] min infusion for 60 minutes) as well as to non-NO-dependent pressor stimuli, namely, vasopressin (2, 4, and 8 ng [middle dot] kg) and phenylephrine (0.5, 1, and 2 [micro sign]g [middle dot] kg) given as IV boluses, were assessed both under control conditions and during suppression of autonomic reflexes by hexamethonium (30 mg [middle dot] kg IV bolus + 1.5 mg [middle dot] kg () [middle dot] min infusion). Rather than being reduced, the pressor responses to L-NMMA were 39% and 71% larger in the control and areflexic conditions, respectively, than those observed in WKY (both P
ISSN:0194-911X
1524-4563
DOI:10.1161/01.hyp.32.4.735