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A role for tubular Na+/H+ exchanger NHE3 in the natriuretic effect of the SGLT2 inhibitor empagliflozin

A role for tubular Na+/H+ exchanger NHE3 in the natriuretic effect of the SGLT2 inhibitor... Inhibitors of the proximal tubular sodium glucose cotransporter SGLT2 are natriuretic and they lower blood pressure. There are reports that the activities of SGLT2 and the Na+-H+-exchanger, NHE3, are coordinated. If so, then part of the natriuretic response to an SGLT2 inhibitor is mediated by suppressing NHE3. To examine this further, we compared the effects of the SGLT2 inhibitor, empagliflozin, on urine composition and systolic blood pressure (SBP) in non-diabetic mice with tubule-specific NHE3 knock-down (NHE3-ko) and wild-type littermates (WT). A single dose of empagliflozin, titrated to cause minimal glucosuria, increased urinary excretion of Na+ and bicarbonate, and raised urine pH in WT, but not in NHE3-ko. Chronic empagliflozin treatment tended to lower SBP despite higher renal renin mRNA expression, and lowered the ratio of SBP to renin mRNA, indicating volume loss. This effect of empagliflozin depended on tubular NHE3. In diabetic Akita mice, chronic empagliflozin enhanced phosphorylation of NHE3 (S552/S605), changes previously linked to lesser NHE3-mediated reabsorption. Chronic empagliflozin also increased expression of genes involved with renal gluconeogenesis, bicarbonate regeneration, and ammonium formation. While this could reflect compensatory responses to acidification of proximal tubular cells resulting from reduced NHE3 activity, these effects were at least in part independent of tubular NHE3 and potentially indicated metabolic adaptations to urinary glucose loss. Moreover, empagliflozin increased luminal α-ketoglutarate, which may serve to stimulate compensatory distal NaCl reabsorption, while co-generated and excreted ammonium balances urine losses of this "potential bicarbonate". The data implicate NHE3 as a determinant of the natriuretic effect of empagliflozin. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png American Journal of Physiology-Renal Physiology The American Physiological Society

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References (76)

ISSN
1931-857x
eISSN
1522-1466
DOI
10.1152/ajprenal.00264.2020
Publisher site
See Article on Publisher Site

Abstract

Inhibitors of the proximal tubular sodium glucose cotransporter SGLT2 are natriuretic and they lower blood pressure. There are reports that the activities of SGLT2 and the Na+-H+-exchanger, NHE3, are coordinated. If so, then part of the natriuretic response to an SGLT2 inhibitor is mediated by suppressing NHE3. To examine this further, we compared the effects of the SGLT2 inhibitor, empagliflozin, on urine composition and systolic blood pressure (SBP) in non-diabetic mice with tubule-specific NHE3 knock-down (NHE3-ko) and wild-type littermates (WT). A single dose of empagliflozin, titrated to cause minimal glucosuria, increased urinary excretion of Na+ and bicarbonate, and raised urine pH in WT, but not in NHE3-ko. Chronic empagliflozin treatment tended to lower SBP despite higher renal renin mRNA expression, and lowered the ratio of SBP to renin mRNA, indicating volume loss. This effect of empagliflozin depended on tubular NHE3. In diabetic Akita mice, chronic empagliflozin enhanced phosphorylation of NHE3 (S552/S605), changes previously linked to lesser NHE3-mediated reabsorption. Chronic empagliflozin also increased expression of genes involved with renal gluconeogenesis, bicarbonate regeneration, and ammonium formation. While this could reflect compensatory responses to acidification of proximal tubular cells resulting from reduced NHE3 activity, these effects were at least in part independent of tubular NHE3 and potentially indicated metabolic adaptations to urinary glucose loss. Moreover, empagliflozin increased luminal α-ketoglutarate, which may serve to stimulate compensatory distal NaCl reabsorption, while co-generated and excreted ammonium balances urine losses of this "potential bicarbonate". The data implicate NHE3 as a determinant of the natriuretic effect of empagliflozin.

Journal

American Journal of Physiology-Renal PhysiologyThe American Physiological Society

Published: Oct 1, 2020

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