Abstract
Renovascular hypertension has robust effects on control of blood pressure, including an impairment in baroreflex mechanisms, which involves oxidative stress. Although α-lipoic acid (LA) has been described as a potent antioxidant, its effect on renovascular hypertension and baroreflex sensitivity (BRS) has not been investigated. In the present study we analyzed the effects caused by chronic treatment with LA on blood pressure, heart rate and baroreflex sensitivity (sympathetic and parasympathetic components) in renovascular hypertensive rats. Male Wistar rats underwent 2-Kidney-1-Clip (2K1C) or sham surgery and were maintained untouched for four weeks to develop hypertension. Four weeks post-surgery, rats were treated with LA (60 mg/kg) or saline for 14 days orally. On the 15th day mean arterial pressure (MAP) and heart rate (HR) were recorded. In addition, baroreflex sensitivity test using phenylephrine (8 µg/kg, i.v.) and sodium nitroprusside (25 µg/kg, i.v.) was performed. Chronic treatment with LA decreased blood pressure in hypertensive animals; however, no significant changes in baseline HR were observed. Regarding baroreflex, LA treatment increased the sensitivity of both the sympathetic and parasympathetic components. All parameters studied were not affected by treatment with LA in normotensive animals. Our data suggest that chronic treatment with LA promotes antihypertensive effect and improves baroreflex sensitivity in rats with renovascular hypertension.
Highlights
Introduction αLipoic acid (LA), known as 1,2-dithiolane-3-pentanoic acid or thioctic acid, is a disulfide antioxidant with one chiral center that exists in both R- and S-enantiomeric forms
In addition rats from the 2K1C + lipoic acid (LA) group presented a reduction in blood pressure when compared to
These results corroborate other studies which have been reported that common antioxidants for clinical use and experimental trials such as ascorbic acid (AAC) and N-acetylcysteine (NAC) were able to delay or prevent the development of different types of hypertension
Summary
Acute intravenous infusion of ascorbic acid, a well-known antioxidant, increases baroreflex sensitivity in patients with cardiac dysfunction [43,44] According to these related studies, as well as in the present investigation, administration of antioxidants had no effect on baroreflex function in normotensive animals [42,43], suggesting that anti-oxidant therapy in the absence of oxidative stress has no influence on baroreflex sensitivity. A number of drugs used for the treatment of hypertension, hypercholesterolaemia and coronary artery disease such as the statins, AT1 (angiotensin II receptor type 1) antagonists and ACE inhibitors have been shown to decrease NADPH oxidase-derived superoxide and ROS production [46,47,48] These therapies could repair the pro-oxidants levels and reestablish the regular conditions of the baroreflex sensitivity as well as cardiovascular parameters in the renovascular hypertension
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