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Effects of L-arginine on endothelial and cardiac function in rats with heart failure
Q Feng1, A J Fortin, X Lu
1London Health Sciences Centre Research Inc., Department of Medicine, University of Western Ontario, Canada. qfeng@julian.uwo.ca
Insights
Chronic oral L-arginine supplementation in rats with heart failure improved blood vessel function at a lower dose. However, this treatment did not enhance overall cardiac performance in the heart failure model.
Area of Science:
- Cardiovascular Science
- Pharmacology
- Physiology
Background:
- Heart failure is often associated with impaired endothelial function.
- L-arginine is a crucial substrate for nitric oxide synthesis, vital for vascular health.
- Reduced plasma L-arginine levels are observed in heart failure conditions.
Purpose of the Study:
- To investigate the impact of chronic oral L-arginine treatment on endothelial and cardiovascular function in a rat model of heart failure.
- To determine the dose-dependent effects of L-arginine on vascular reactivity and cardiac performance.
Main Methods:
- Induction of heart failure in rats via coronary artery ligation.
- Administration of L-arginine (12.5 or 50 g/l) or placebo in drinking water for 8 weeks.
- Assessment of plasma L-arginine levels, ex vivo endothelium-dependent relaxation of aortic rings, and in vivo hemodynamic parameters.
Main Results:
- Plasma L-arginine levels were significantly lower in heart failure rats compared to sham-operated controls.
- Low-dose (12.5 g/l) L-arginine treatment improved endothelium-dependent relaxation in aortic rings from heart failure rats.
- Neither low nor high-dose L-arginine treatment significantly improved hemodynamic parameters in heart failure rats.
Conclusions:
- Chronic oral L-arginine supplementation at 12.5 g/l enhances endothelial function in rats with heart failure.
- Higher doses of L-arginine did not yield similar improvements in vascular relaxation.
- L-arginine treatment failed to improve in vivo cardiac function despite improvements in endothelial-dependent relaxation.
Abstract:
We examined the effects of chronic oral L-arginine treatment on endothelial and cardiovascular function in rats with heart failure induced by coronary artery ligation. Both heart failure and sham-operated rats were treated with either L-arginine in drinking water (12.5 or 50 g/l) or water placebo for 8 weeks following surgery. Plasma L-arginine levels in heart failure rats (153 +/- 11 microM) were lower than sham rats (201 +/- 13 microM, P < 0.05). The lower dose L-arginine treatment improved endothelium-dependent relaxation of isolated aortic rings of heart failure rats, while the higher dose of L-arginine treatment did not. Neither low nor high dose of L-arginine treatment improved hemodynamic parameters in heart failure rats. Thus, chronic oral L-arginine treatment at a dose of 12.5 g/l in drinking water improves endothelium-dependent relaxation, but fails to improve in vivo cardiac function in rats with heart failure.