Salt‐deficient diet does not attenuate the development of slowly progressive ANG II‐dependent hypertension in Cyp1a1‐Ren2 transgenic rats

Abstract

The present study was performed to determine the effects of dietary salt restriction on conscious systolic blood pressure (SBP), and 24‐hour urine flow and urinary sodium and protein excretion in Cyp1a1‐Ren2 rats with slowly progressive ANG‐II dependent hypertension. Adult male Cyp1a1‐Ren2 rats (n=5–6/group) were fed either a normal salt (0.6%) or salt‐deficient diet (<0.01%) containing indole‐3‐carbinol (I3C; 0.15%, wt/wt) to induce slowly progressive ANG II‐dependent hypertension. Both normal salt and salt‐deficient groups fed an I3C‐containing diet showed increases in SBP by day 4 of treatment (134±3 to 162±3 and 147±4 to 160±3 mmHg, respectively, P<0.001) and reached similar SBP levels by day 16 (207±8 vs. 194±7 mmHg, NS). Induced rats on salt‐deficient diet exhibited markedly reduced 24‐hour urinary sodium excretion (74.4±15.8 to 0.20±0.07 mEq/day, P<0.001) and urine output (10.2±1.3 vs. 18.8±3.5 mL/day, P<0.05. Urinary protein excretion increased similarly in response to I3C administration regardless of dietary salt intake (7.5±0.8 to 25.2±4.4, and 6.6±0.3 to 35.7±5.7 mg/d, respectively, P<0.05). These findings demonstrate that dietary salt restriction does not attenuate the development of slowly progressive ANG II‐dependent hypertension or the associated proteinuria in Cyp1a1‐Ren2 transgenic rats.Support: NHLBI, Tulane COBRE in Hypertension and Renal Biology.