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

Background and objectives 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 pre ssure. The thiol compound, N-acetyl cysteine, normalizes elevated blood pre ssure in SHRs by binding excess endogenous aldehydes and normalizing membra ne Ca2+ channels and cytosolic free calcium. The aim of the present study w as to investigate whether a dietary supplementation of an endogenous fatty acid, alpha-lipoic acid, another thiol compound that is known to increase t issue cysteine and glutathione, can lower blood pressure and normalize asso ciated biochemical and histopathological changes in SHRs, Methods and results Starting at 12 weeks of age, animals were divided into three groups of six animals each. Animals in the Wistar-Kyoto (WKY) rat con trol 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, platel et [Ca2+](i), plasma insulin and liver, kidney and aortic aldehyde conjugat es were significantly higher in SHR controls as compared with WKY rat contr ols and the SHR lipoic acid group, SHR controls also showed smooth muscle c ell hyperplasia in the small arteries and arterioles of the kidneys. Conclusions Dietary alpha-lipoic acid supplementation in SHRs lowered the s ystolic blood pressure, cytosolic [Ca2+](i), blood glucose and insulin leve ls, and tissue aldehyde conjugates, and attenuated adverse renal vascular c hanges. J Hypertens 2000, 18:567-573 (C) Lippincott Williams & Wilkins.