Effect of moderately high dietary salt and lipoic acid on blood pressure in Wistar-Kyoto rats.

Background: Approximately one-half of hypertensive individuals are salt sensitive, and animal models of human hypertension also exhibit increased blood pressure when exposed to high-salt diets. Salt sensitivity is associated with insulin resistance, which results in altered glucose metabolism, increasing aldehydes. Previously, the authors have shown that a high-salt diet (8% NaCl) caused an increase in blood pressure, tissue aldehyde conjugates and cytosolic free calcium, with resulting adverse renal vascular changes, in Wistar-Kyoto rats. Treatment with lipoic acid (LA) prevented an increase in blood pressure and attenuated biochemical and histopathological changes.

Objectives: The objective of the present study was to investigate the effect of a moderately high-salt (MHS) diet (4% NaCl) on these same parameters, and the modulating effect of LA in Wistar-Kyoto rats.

Methods: At seven weeks of age, animals were divided into three groups. The normal-salt group was given a diet containing 0.7% NaCl; the MHS group was given a diet containing 4% NaCl; and the MHS+LA group was given a diet containing 4% NaCl plus LA (500 mg/kg diet) for 10 weeks.

Results: At the end of the study, animals in the MHS group did not show any increase in systolic blood pressure, platelet cytosolic free calcium and tissue aldehyde conjugates. Furthermore, there were no adverse effects in renal vascular morphology compared with the normal salt group. In the MHS+LA group, LA did not lower blood pressure or affect other biochemical and histopathological parameters.

Conclusion: The present study suggests that moderately high sodium intake, over a short period, may not have any adverse effect and that LA does not lower blood pressure in normotensive rats.