Abstract: SA-PO1108

Changes in Phosphorylation and Expression of Sodium Transporters in Pre-Eclampsia Detected in Urinary Exosomes

Session Information

  • Salt and Hypertension
    November 04, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Hypertension

  • 1104 Hypertension: Clinical and Translational - Salt and Hypertension

Authors

  • Mount, Peter F., Austin Health, Melbourne, Victoria, Australia
  • Power, David A., Austin Health, Melbourne, Victoria, Australia
  • Hu, CHIH-CHIANG, Institute for Breathing and Sleep, Melbourne, Victoria, Australia
  • Katerelos, Marina, Austin Health, Melbourne, Victoria, Australia
  • Choy, Suet-Wan, Austin Health, Melbourne, Victoria, Australia
  • Cook, Natasha, Austin Health, Melbourne, Victoria, Australia
  • Crosthwaite, Amy A, Austin Health, Melbourne, Victoria, Australia
  • Pell, Gabrielle Louise, Mercy Health, Melbourne, Vic, New South Wales, Australia
  • Paizis, Kathy, Austin health, Heidelberg, New South Wales, Australia
  • Walker, Susan Phillipa, Mercy Health, Melbourne, Vic, New South Wales, Australia
Background

PE (pre-eclampsia) is characterized by hypertension, vasoconstriction, proteinuria and renal sodium retention. It is unknown whether expression or phosphorylation of the distal renal tubular sodium transporters (NKCC2, NCC and EnaC) changes in women with PE.

Methods

A cross-sectional study of 18 PE patients, 22 normotensive pregnant women (NP) and 20 normal women (NC) was performed. Exosomes were isolated from urine by ultracentrifugation. Expression of sodium transporters was analysed by Western Blot corrected for expression of the exosome marker CD9. Statistical comparisons were made by ANOVA and a post-hoc test.

Results

Expression of NKCC2 was increased 1.6-fold in PE (ANOVA p=0.046, post-hoc=ns). Phosphorylation on the SPAK/OSR1 activation site T101/105 was reduced 1.9-fold (ANOVA p=0.030; PE vs NP p<0.05) while phosphorylation of the activating PKA S130 site was increased 2.8-fold (ANOVA p<0.001; PE vs NP p<0.01) in PE compared to NP. There was no difference in expression of NCC but phosphorylation of the SPAK/OSR1 site T60 was reduced 2.5-fold (ANOVA p=0.008; PE vs NP p<0.05). Expression of the alpha (ANOVA p<0.001; PE vs NP p<0.01) and full-length gamma ANOVA (p<0.001; PE vs NP p<0.05) subunits of ENaC was increased 6.0-fold and 2.7-fold, respectively, in PE compared to NP. There was a non-significant trend to increased expression of the cleaved 50 kD form of gamma ENaC in PE (ANOVA p=0.06).

Conclusion

These data suggest a role for increased activity of ENaC and NKCC2 in mediating sodium-retention in PE, occurring despite reduced signalling through the WNK/SPAK/OSR1 pathway.

Fig. 1: Phosphorylation of NKCC2 on S130 and T101/105. S130 is a PKA and AMPK phosphosite. T101 and 105 are SPAK/OSR1 phosphosites. (A) pS130/NKCC2: ANOVA p<0.001. PE vs NP, p<0.01; PE vs NC p<0.01. (B) pT101&105/NKCC2: ANOVA p=0.03. PE vs NP, p<0.05.