High fat diet increases salt sensitivity and promotes hypertension and kidney inflammation/injury in Dahl salt sensitive rats

Abstract

Salt sensitivity of blood pressure and renal inflammation/injury are common in obesity associated hypertension. We and others have previously reported that high fat (HF) diet promotes hypertension in Dahl salt sensitive (SS) male rats ingesting a “normal” salt diet (NS, 0.3% NaCl). It is unclear if the HFNS diet would induce renal inflammation/injury and if a low salt intake would reduce blood pressure and renal inflammation/injury in this model of obesity‐associated hypertension. Therefore in the current study, Dahl SS male rats were fed a normal fat (NF, 10% kcal from fat) and HF (60% kcal from fat) diet with different salt contents for 24–26 weeks after weaning (3 weeks of age). HFNS (n=9) rats had a much higher MAP than NFNS rats (n=10) at the end of the study (158±1 mmHg versus 130±1 mmHg, P<0.05). However, in low salt fed rats (LS, 0.1% NaCl), MAP at the end of the study was only slightly higher in HFLS (n=4) than NFLS (n=5) rats (131±1 mmHg vs 121±3 mmHg, P<0.05). Renal tissues were taken from rats at 24 weeks after feeding. Renal injury was histologically characterized as the grade of tubular proteinosis, tubular atrophy, glomerulofibrosis, and interstitial fibrosis. Renal inflammation was identified by counting the infiltration of macrophages (CD68) and T cells (CD3) in cortex and medulla. HFNS feeding caused much more severe renal injury and higher CD68 infiltration than NFNS, but this was not observed in HFLS fed rats. NSNF rats also showed more CD68 infiltration than all LS rats. HFNS and NFNS rats showed similarly higher CD3 infiltrations than all LS rats. HFNS fed rats exhibited significantly increased expression of renal proliferating cell nuclear antigen (PCNA, a cellular proliferation marker) but this was not seen in HFLS fed rats. Body weight was not significantly greater, but visceral adipose accumulation was higher, in HFNS and HFLS rats compared to NFNS and NFLS fed rats, respectively. HF fed rats did not show significant alterations in plasma levels of fasting glucose, insulin, leptin, aldosterone or serum creatinine compared to NF rats. Our studies suggested that high fat diet associated hypertension and renal inflammation/injury in Dahl SS male rats are both salt‐sensitive, but are not associated with obvious metabolic disorders. Low salt diet may be useful in protecting against obesity associated hypertension and renal inflammation/injury.Support or Funding InformationNIH NHLBI 2P01HL070687This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.