Dietary α-lipoic acid supplementation lowers blood pressure in spontaneously hypertensive rats

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Abstract
In spontaneously hypertensive rats (SHRs), excess endogenous aldehydes bind sulfhydryl groups of membrane proteins, altering membrane Ca2+ channels and increasing cytosolic free calcium and blood pressure. The thiol compound, N-acetyl cysteine, normalizes elevated blood pressure in SHRs by binding excess endogenous aldehydes and normalizing membrane Ca2+ channels and cytosolic free calcium. The aim of the present study was to investigate whether a dietary supplementation of an endogenous fatty acid, alpha-lipoic acid, another thiol compound that is known to increase tissue cysteine and glutathione, can lower blood pressure and normalize associated biochemical and histopathological changes in SHRs. Starting at 12 weeks of age, animals were divided into three groups of six animals each. Animals in the Wistar- Kyoto (WKY) rat control group and the SHR control group were given a normal diet, and the SHR-lipoic acid group was given a diet supplemented with lipoic acid (500 mg/kg feed) for the next 9 weeks. After 9 weeks, systolic blood pressure, platelet [Ca2+]i, plasma insulin and liver, kidney and aortic aldehyde conjugates were significantly higher in SHR controls as compared with WKY rat controls and the SHR lipoic acid group. SHR controls also showed smooth muscle cell hyperplasia in the small arteries and arterioles of the kidneys. Dietary alpha-lipoic acid supplementation in SHRs lowered the systolic blood pressure, cytosolic [Ca2+]i, blood glucose and insulin levels, and tissue aldehyde conjugates, and attenuated adverse renal vascular changes.