Long-term High Salt Diet Causes Hypertension and Decreases Renal Expression of Vascular Endothelial Growth Factor in Sprague-Dawley Rats.

We seek to determine: 1) whether a long-term high salt diet induces hypertension and renal injury in Sprague-Dawley (SD) rats and 2) whether the high salt diet-induced hypertension and renal injury are associated with decreased renal VEGF expression. Twelve 10-wk-old male SD rats received a high salt diet (HS, 8%) and twelve SD rats received a normal salt diet (NS, 0.5 %) for 8 weeks. Using a tail cuff, weekly monitoring showed that blood pressure increased significantly after 6, 7, & 8 wks in HS group, compared to NS group (P<0.01). At 4 wks and 8 wks of diet, mean arterial pressure (MAP) was determined in conscious rats by continuous monitoring through a catheter placed in the carotid artery. MAP was not significantly different between HS and NS group in 4 wks, but was significantly higher in HS than NS group (140+/-5.3 vs.112+/-2.2 mmHg; P<0.01) in 8 wks. Increased proteinuria and albuminuria were associated with marked renal histological abnormalities in HS group, compared to those in NS group. Northern blot and ELISA demonstrated that 8 wks of HS diet significantly decreased renal expression of VEGF mRNA and protein, compared to NS group (P<0.01). In 8 wks, total urinary excretion of sFlt-1 was significantly higher in HS than NS group (9.28+/-1.05 vs. 2.05+/-0.55 ng/day; P<0.01) whereas the plasma levels of sFlt-1 remained stable. These results suggest that a long-term HS diet induces renal injury and hypertension, which are associated with decreased renal VEGF expression in normotensive rodent animals.