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Blunted cardiovascular growth induction during prolonged nitric oxide synthase blockade
J D Banting1, K E Thompson, P Friberg
1Department of Pharmacology and Toxicology, Queen's University, Kingston, Ontario, Canada.
Hypertension (Dallas, Tex. : 1979)
|October 6, 1997
Summary
Hypertension induced by blocking nitric oxide synthesis did not cause significant cardiac growth or vascular changes. Ornithine decarboxylase (ODC) activation was transient, suggesting pressure alone may not drive cardiovascular remodeling.
Area of Science:
- Cardiovascular Physiology
- Enzymology
- Hypertension Research
Background:
- Hypertension is a major risk factor for cardiovascular disease.
- Cardiovascular growth (hypertrophy) is a key pathological adaptation to sustained pressure overload.
- The role of ornithine decarboxylase (ODC) in mediating pressure-induced cardiovascular remodeling is not fully understood.
Purpose of the Study:
- To investigate the activation profile of ornithine decarboxylase (ODC) in cardiovascular tissues during L-NAME-induced hypertension.
- To correlate ODC activation with structural changes in the heart and blood vessels.
- To determine if pressure overload alone is sufficient to induce cardiovascular growth.
Main Methods:
- Rats were treated with N(omega)-nitro-L-arginine methyl ester (L-NAME) to induce hypertension.
- Mean arterial pressure and ODC activity were measured at various time points (4 hours to 12 days).
- Vascular resistance and cardiac mass were assessed after 12 days of L-NAME treatment, with and without L-ornithine supplementation.
Main Results:
- L-NAME induced marked hypertension but only marginal and transient ODC activation in the left ventricle and aorta.
- A slightly prolonged but transient ODC activation was observed in the mesenteric vascular bed.
- Hindlimb vascular resistance increased modestly, and no cardiac hypertrophy was detected after 12 days of L-NAME treatment.
Conclusions:
- Sustained hypertension induced by NO synthase blockade does not lead to significant cardiac hypertrophy or substantial vascular remodeling.
- ODC activation in response to hypertension is transient and may not be the primary driver of cardiovascular growth.
- These findings suggest that elevated pressure alone may be insufficient to induce cardiovascular growth, or L-NAME might have non-specific inhibitory effects on growth processes.