Adenovirus-mediated Overexpression of Na + /H + Exchanger NHE3 Selectively in The Proximal Tubules of The Kidney Elevates Blood Pressure in Adult Male C57BL/6J Mice

The prevalence of arterial hypertension is increasing with a lifetime risk of developing hypertension reaching >90% for men and women aged 55 to 65 years. Most elderly patients with hypertension require treatments with multiple classes of antihypertensive drugs. However, only ~50% of hypertensive patients have their blood pressure adequately controlled, whereas remaining patients continue to develop poorly controlled hypertension even treated with multiple antihypertensive drugs. Poorly controlled hypertension is especially prevalent in aging men and postmenopausal women. The mechanisms underlying poorly controlled hypertension in aging men and postmenopausal women remain poorly understood. The Na + /H + exchanger 3 (NHE3), a ~85 kDa protein encoded by the SLC9A3 gene, is the most important Na + transporter in the proximal tubules responsible for reabsorbing >50% of filtered Na + in the proximal tubules. There is strong evidence showing that NHE3 in the proximal tubules is dysregulated or inappropriately upregulated in animal models of essential or angiotensin II (Ang II)-induced hypertension. The present study tested the hypotheses that overexpression of NHE3 selectively in the proximal tubules elevates blood pressure in aging >20-month-old male C57BL/6J mice. To test the hypothesis, three groups (n=5-10 each) of mice were first implanted with a telemetry probe to obtain basal blood pressure and measure basal kidney function using metabolic cage, respectively. One week later, adenovirus-mediated, the Sglt2 promoter-driven overexpression of NHE3 selectively in the proximal tubules was performed in two groups of mice using Ad-Sglt2-EGFP-T2A-NHE3. There were no significant differences in blood pressure and kidney function parameters under basal conditions. Compared with the time-control group, systolic blood pressure increased from basal 118 ± 2 mmHg to 126 ± 2 mmHg (n=10, P <0.05) one week after the overexpression of NHE3 in the proximal tubules. The blood pressure was further increased to 132 ± 4 mmHg (n=5, P <0.01) 2 weeks after NHE3 overexpression in the proximal tubules. The increases in blood pressure by proximal tubule-selective overexpression of NHE3 were associated with significant decreases in urinary sodium excretion from basal 252.6 ± 5.3 μmol/24h to 201.2 ± 13.5 μmol/24h, urinary potassium excretion from basal 341.9 ± 12.8 μmol/24h to 260.8 ± 18.5 μmol/24h, and urinary chloride excretion from basal 323.0 ± 10.1 μmol/24h to 218.0 ± 16.5 μmol/24h, respectively. However, there was no difference in heart rate, heart wt., kidney wt. and blood hematocrit levels between three groups (n.s.). These results provide the proof of concept evidence that the dysregulation or inappropriate upregulation of NHE3 in the proximal tubules of the kidney may elevate arterial blood pressure in animal models of hypertension. This work was supported in part by 2R01DK102429-03A1, 2R01DK067299-10A1, and 1R01DK123144-01, respectively. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.