Kidney Week

Abstract: TH-PO509

Loss-of-Function Mutation in the Epithelial Na+ Channel Alpha Subunit Reduces Salt/Aldosterone-Induced Hypertension in Mice

Session Information

• Fluid and Electrolytes: Basic - I
  October 25, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Fluid and Electrolytes

• 901 Fluid and Electrolytes: Basic

Authors

• Sheng, Shaohu, University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Shaohu Sheng,

• Ray, Evan C., UPMC, Pittsburgh, Pennsylvania, United States

Evan C. Ray,

• Mutchler, Stephanie, University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Stephanie Mutchler,

• Chen, Jingxin, University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Jingxin Chen,

• Marciszyn, Allison L., University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Allison L. Marciszyn,

• Wang, Xueqi, University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Xueqi Wang,

• Kleyman, Thomas R., University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Thomas R. Kleyman,

Background

Epithelial Na⁺ channels (ENaC) have an important role in regulating blood pressure and extracellular [K⁺]. We previously identified a point mutation in mouse ENaC alpha subunit (H283R) that significantly enhanced Na⁺ self-inhibition, reflecting a reduced open probability specifically due to extracellular Na⁺. Its homologous human variant (H255R) has similar effects. In this study, we investigated whether the loss-of-function mutation H283R would protect mice from salt and aldosterone-induced hypertension.

Methods

H283R was introduced into the exon 2 of gene Scnn1a (encoding alpha ENaC) in C57/BL6J mice using CRISPR/Cas9-mediated gene editing method. Six homozygous H283R mice and six littermates were implanted with radio telemeters to record blood pressure, heart rate and activity level. Following seven days recording under normal salt (0.5% NaCl) diet, mice were fed with a high salt (4% NaCl) diet and implanted with minipumps for aldosterone infusion. Data recording continued for four additional weeks.

Results

There were no significant differences in pulse, systolic, diastolic and mean arterial pressures, heart rates, activity and blood electrolytes under normal Na⁺ diet conditions, except for a modest difference in blood [Na⁺]. Blood pressures displayed normal diurnal variation. Blood pressures gradually increased in all mice after switching to high salt diet plus aldosterone infusion. However, H283R mice displayed significantly lower systolic, diastolic and mean arterial pressures than wild type mice on multiple days (p < 0.05). Both day and night blood pressures showed significant differences between the two groups. Heart rate and activity were similar in the two groups. Plasma aldosterone levels measured at the end of the experiment were not significantly different. We did not observe significant differences in Na⁺ and K⁺ concentrations in blood and urine samples in these mice.

Conclusion

The Na⁺ self-inhibition enhancing mutation H283R in ENaC alpha subunit protects mice from high salt and aldosterone-induced hypertension. Our observations suggest that certain loss-of-function human ENaC variants like H255R may protect individuals from the development of salt-sensitive hypertension.

Funding

• NIDDK Support