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Abstract: FR-PO318

In Obese ZSF1 Rats Salt-Sensitivity of Blood Pressure Is Positively Related to Free Sodium in Skin and Negatively to Bound Sodium in Skin

Session Information

Category: Hypertension and CVD

  • 1403 Hypertension and CVD: Mechanisms

Authors

  • Nguyen, Isabel T.N., University Medical Center Utrecht, Utrecht, Netherlands
  • Samuelsson, Anne-Maj, University of Bergen, Bergen, Norway
  • Joles, Jaap A., University Medical Center Utrecht, Utrecht, Netherlands
  • Verhaar, Marianne C., University Medical Center Utrecht, Utrecht, Netherlands
Background

Last year we reported that blood pressure in Zucker fatty/spontaneously hypertensive heart failure F1 hybrid (ZSF1) rats exposed to deoxycorticosterone acetate (DOCA) and fed a high salt diet is more salt-sensitive in obese than in lean ZSF1 rats (p<0.0001). Moreover, obese females were even more salt-sensitive than obese males (p<0.01). Only male obese ZSF1 were hyperglycemic and manifested glycosuria (Nguyen et al. ASN 2017). This follow-up study dissects the role of free and bound sodium in the skin on the differences in salt-sensitivity between female and male obese ZSF1 rats.

Methods

Male and female ZSF1 rats, lean (N=4-6/subgroup) and obese (N=6-8/subgroup), were either implanted with a DOCA pellet and fed a high salt diet (6% NaCl) or with a placebo pellet and fed a normal salt diet from 19 weeks of age. Every two weeks, from 18 (i.e prior to pellet implantation) to 26 weeks of age, systolic blood pressure (SBP) and 24-hours urine was collected. To further elucidate the diverging natriuresis-pressure relations in the obese ZSF1, skin sodium content was determined at 26 weeks (N=2-4/group).

Results

On placebo, obese male ZSF1 showed more free sodium in skin than obese females (p=0.03). However, on DOCA+salt, obese females showed higher free sodium compared to obese males (p=0.053). The interaction between sex and DOCA+salt on free sodium in skin was very significant (p=0.002). For bound sodium in skin changes were in the reverse direction (interaction: p=0.036). Overall (N=6), the increase in blood pressure/natriuresis on DOCA+salt from week 18 to week 26 correlated positively with free sodium in skin (r=0.91, P=0.01; Figure 1A) and tended to correlate negatively with bound sodium in skin (r=0.69, P=0.13; Figure 1B).

Conclusion

Our results indicate that in obese ZSF1 rats inverse relations exist between salt sensitivity of blood pressure and free versus bound sodium in the skin. Compartmentalization of sodium in the skin is influenced by sex, which in this model may be associated with differences in glycemia.

Funding

  • Private Foundation Support