Sex dependent differences in collecting duct renin during high salt intake

Abstract

Collecting duct (CD) renin is upregulated during Ang II‐dependent hypertension. In this study we examined if CD renin exhibits sex differences during changes in salt intake in 19 Sprague‐Dawley rats distributed in 4 groups [1) Controls male (n=5); 2) Controls female (n=5); HS male (n=5); and HS female (n=4) fed a normal and HS diet (8% NaCl). Baseline systolic blood pressure (SBP) was not different between males and female rats (males: 116±3 vs. female: 119±2 mmHg) nor after 2‐weeks fed a HS diet (male 126±2 vs. female: 128±2 mmHg). Although renin mRNA and protein levels examined by qRT‐PCR and Western blot in renal medullary tissues were similar in male and female rats under control conditions [Controls male: mRNA= 1.0±0.4 AU; protein=1.0±0.1 DU vs. Controls female: mRNA=0.3±0.1AU; protein=0.8±0.1 DU)]; HS diet intake significantly increased the CD renin transcript and protein levels in females but not in male rats [mRNA=(HS male: 1.5±0.1 vs. HS female: 3.4±0.6 AU); protein= (HS male: 1.0±0.3 DU vs. HS female: 1.8 ±0.7 DU). These data suggest that although there is not sex difference in CD renin gene expression under basal conditions, HS intake appears to stimulate renin in distal nephron segment only in female rats. Future studies are planned to determine whether HS intake during chronic Ang II infusion leads to sexual dimorphisms of blood pressure during Ang II‐dependent hypertension.