Abstract 120: Reversal of Hypertension Stops, but Does Not Reverse, Renal T-cell Infiltration in the Dahl Salt-sensitive Rat

Abstract

In previous chronic servo control experiments we showed that increased renal perfusion pressure (RPP) amplifies renal T-cell infiltration in Dahl salt-sensitive (SS) rats. Renal T-cell infiltration was significantly higher in the right-hypertensive kidneys vs. the left servo-controlled kidneys of SS rats fed high salt (HS) for 7-days. There was no significant difference in T-cell infiltration in sham rats (both kidneys exposed to comparable RPPs). Here we use the chronic servo control system to determine whether the reversal of salt-sensitive hypertension reverses renal T-cell infiltration in SS rats. An aortic balloon occluder was placed around the aorta, between the renal arteries to electronically servo-control RPP to the left kidney. Arterial catheters were used to measure MAP above and below the occluder (n=5). Baseline RPPs were measured on a control salt diet (0.4% NaCl) for 3-days (average left RPP, 124±1mmHg) after which rats were switched to a HS diet (4.0% NaCl) for 14-days. During the first 7-days of HS both kidneys were exposed to uncontrolled hypertension. After 7-days a servo control system was used to bring the RPP to the left kidney (the reversal kidney) back to the average control level, where it was held for the next 7-days of HS (from 139±2mmHg to 125±2mmHg). It was found that reversal of hypertension prevented a further increase of renal T-cell infiltration but the number of infiltrated T-cells did not diminish. Moreover, the number of T-cells in the left-reversal kidney was significantly higher than in the continuously-controlled, left-servo kidney despite comparable final RPPs (129±2mmHg to the left-servo kidney vs. 125±2mmHg to the left-reversal kidney). T-cell infiltration in the left-reversal kidney was comparable to the left-sham kidneys, in which in the final RPP was 148±2mmHg. In ‘T-cells per kidney’- CD3+ (mature): Reversal=287x10 3 ±65x10 3 Servo=78x10 3 ±12x10 3 Sham=186x10 3 ±47x10 3 . CD3+CD4+ (helper): Reversal=95x10 3 ±27x10 3 Servo=32x10 3 ±5x10 3 Sham=86x10 3 ±26x10 3 . CD3+CD8+ (cytotoxic): Reversal=196x10 3 ±42x10 3 Servo=42x10 3 ±7x10 3 Sham=102,082x10 3 ±23x10 3 We conclude that reversal of blood pressure alone, for 1-week, while HS intake is continued, stops but does not reverse renal T-cell infiltration in SS rats.