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Sex Differences in Systemic and Renal Tissue Urea Concentrations
Author(s) -
Boesen Erika Ingrid,
WangFrance Jun,
Rahman Shamma Shakila
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.lb532
Subject(s) - urea , medicine , endocrinology , osmotic concentration , dietary protein , excretory system , high protein diet , low protein diet , urine , renal function , chemistry , biology , biochemistry , body weight
Inner medullary urea accumulation is believed to play a key role in determining urinary concentrating ability. We had previously studied the effects of different levels of dietary protein concentration on renal excretory function in mice as a test of renal urea handling. Unexpectedly, we observed an increase of urine flow in male but not female mice when switched to a low protein diet (6% protein). To further investigate this phenomenon, we fed diets containing either a low (6%) or normal (20%) protein content to male and female mice for 7 days (n=7–10/group), followed by collection of plasma and renal tissue for measurement of osmolarity and urea concentration. Plasma osmolarity was significantly lower in female compared with male mice irrespective of diet ( P Sex < 0.05), and both sexes had significantly lower plasma osmolarities on 6% compared with 20% protein diets (by ~5 mOsmol/kg. H 2 O; P Diet <0.001). Dietary protein levels had a significant effect on plasma urea concentration irrespective of sex, with urea concentrations being lower on 6% compared with 20% protein diet ( P Diet < 0.0001). Plasma urea levels were also significantly lower in female compared to male mice independent of diet ( P Sex <0.001). The effect of dietary protein intake varied by sex ( P Sex*Diet <0.01), with plasma urea concentration significantly higher in male compared to female on 20% protein diet ( P <0.05 by post‐hoc test; male 9.7 ± 0.3 mM, female 6.8 ± 0.5 mM) but not on 6% protein diet (P>0.05; male 4.9 ± 0.3 mM, female 4.5 ± 0.1 mM). Inner medullary tissue osmolarity was significantly lower on 6% compared to 20% protein diet, independent of sex ( P Diet <0.01), but there was no significant sex difference ( P Sex =0.8) or difference in the way the sexes responded to diet ( P Sex*Diet =0.8). Dietary protein levels also had a significant effect on inner medullary urea concentration, being lower on 6% compared to 20% protein diet in both male and female mice ( P Diet <0.01). Further, there was a sex difference in inner medullary tissue urea concentration, with male mice showing lower urea concentrations compared to female mice, independent of level of dietary protein content ( P Sex =0.05). There were no significant effects of sex or diet on outer medullary or renal cortical tissue osmolarity, or on outer medullary tissue urea concentration. Renal cortical tissue urea concentration was significantly higher in female compared to male mice, independently of diet ( P Sex <0.01), but there no significant effect of the level of dietary protein content ( P Diet =0.07). Together, our data indicate that there are sex differences in circulating and renal tissue urea concentrations, which we speculate may contribute to sex differences in the effect of dietary protein intake on urinary concentrating ability. Support or Funding Information American Heart Association 17GRNT33661008 This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .