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

2020 ◽  
Vol 319 (4) ◽  
pp. F712-F728 ◽  
Author(s):  
Akira Onishi ◽  
Yiling Fu ◽  
Rohit Patel ◽  
Manjula Darshi ◽  
Maria Crespo-Masip ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Sglt2 Inhibitor ◽  
Urine Ph ◽  
Expression Of Genes ◽  
Urinary Glucose ◽  
Renin Mrna ◽  
Proximal Tubular ◽  
Urine Composition ◽  
Natriuretic Effect ◽  
Akita Mice

Inhibitors of proximal tubular Na+-glucose cotransporter 2 (SGLT2) are natriuretic, and they lower blood pressure. There are reports that the activities of SGLT2 and Na+-H+ exchanger 3 (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 an SGLT2 inhibitor, empagliflozin, on urine composition and systolic blood pressure (SBP) in nondiabetic mice with tubule-specific NHE3 knockdown (NHE3-ko) and wild-type (WT) littermates. A single dose of empagliflozin, titrated to cause minimal glucosuria, increased urinary excretion of Na+ and bicarbonate and raised urine pH in WT mice but not in NHE3-ko mice. 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 cogenerated and excreted ammonium balances urine losses of this “potential bicarbonate.” The data implicate NHE3 as a determinant of the natriuretic effect of empagliflozin.

scholarly journals Cardiovascular protection by combination of the selective nonsteroidal MR antagonist finerenone and the SGLT2 inhibitor empagliflozin in a preclinical model of hypertension-induced end-organ damage

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
P Kolkhof ◽  
E Hartmann ◽  
A Freyberger ◽  
M Pavkovic ◽  
I Mathar ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Low Dose ◽  
Sglt2 Inhibitor ◽  
Organ Damage ◽  
Left Ventricular ◽  
Cardiovascular Protection ◽  
End Organ Damage ◽  
Urinary Glucose ◽  
Dose Combination ◽  
Dose Dependent

Abstract Background The nonsteroidal mineralocorticoid receptor (MR) antagonist finerenone and SGLT2 inhibitors have demonstrated clinical benefits in HFrEF and CKD patients with T2D. Cardiovascular protection with finerenone and the SGLT2 inhibitor empagliflozin in combination in hypertensive cardiorenal disease is unknown. Purpose To test the hypothesis that the combination of finerenone with empagliflozin provides cardiovascular protection in preclinical hypertension-induced end-organ damage. Methods Cardiovascular morbidity and mortality was studied in hypertensive L-NAME (20 mg/L) treated renin-transgenic (mRen2)27 rats. Rats (10–11 weeks old female, n=13–17/group) were treated once daily orally for up to 7 weeks with placebo, finerenone (1 and 3 mg/kg), empagliflozin (3 and 10 mg/kg), or a combination of the respective low doses. Blood pressure (week 1, 3 and 5), urinary (week 2 and 6) and plasma parameters (week 6 and at the end of the study) were determined during the course of the study, while cardiac histology and left ventricular gene expression analysis were performed after study end. Results Empagliflozin induced a strong and dose-dependent increase in urinary glucose excretion which was not influenced by finerenone co-administration in the combination arm. Treatment with 3 mg/kg finerenone and the low dose combination significantly decreased systolic blood pressure (SBP) after 3 and 5 weeks as well as plasma uric acid after 6 weeks. SBP was significantly more reduced in the combination arm vs. the individual monotherapies after 3 weeks. Plasma NT-proBNP was reduced by empagliflozin, finerenone and the combination with similar efficacy. There was a dose-dependent protection from cardiac vasculopathy, cardiac and vascular fibrosis with both agents while low dose combination therapy was more efficient than the respective monotherapy dosages on these cardiac histology parameters. Placebo-treated rats demonstrated a ca. 50% survival rate over the course of 7 weeks while low dose combination provided the most prominent survival benefit (93%). Conclusion Non-steroidal MR antagonism by finerenone and SGLT2 inhibition by empagliflozin confer cardiovascular protection in preclinical hypertensive-induced cardiorenal disease. Combination of these two modes of action at low dosages revealed efficacious reduction in blood pressure, cardiac lesions and mortality indicating a strong potential for combined clinical use in cardiorenal patient populations. FUNDunding Acknowledgement Type of funding sources: Private company. Main funding source(s): BAYER AG

scholarly journals Knockout of Na+-glucose cotransporter SGLT1 mitigates diabetes-induced upregulation of nitric oxide synthase NOS1 in the macula densa and glomerular hyperfiltration

2019 ◽  
Vol 317 (1) ◽  
pp. F207-F217 ◽  
Author(s):  
Panai Song ◽  
Winnie Huang ◽  
Akira Onishi ◽  
Rohit Patel ◽  
Young Chul Kim ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Gene Knockout ◽  
Macula Densa ◽  
Wild Type ◽  
Kidney Weight ◽  
Renin Mrna ◽  
Sglt2 Inhibition ◽  
Glomerular Size ◽  
Akita Mice

Na+-glucose cotransporter (SGLT)1 mediates glucose reabsorption in late proximal tubules. SGLT1 also mediates macula densa (MD) sensing of an increase in luminal glucose, which increases nitric oxide (NO) synthase 1 (MD-NOS1)-mediated NO formation and potentially glomerular filtratrion rate (GFR). Here, the contribution of SGLT1 was tested by gene knockout (−/−) in type 1 diabetic Akita mice. A low-glucose diet was used to prevent intestinal malabsorption in Sglt1−/− mice and minimize the contribution of intestinal SGLT1. Hyperglycemia was modestly reduced in Sglt1−/− versus littermate wild-type Akita mice (480 vs. 550 mg/dl), associated with reduced diabetes-induced increases in GFR, kidney weight, glomerular size, and albuminuria. Blunted hyperfiltration was confirmed in streptozotocin-induced diabetic Sglt1−/− mice, associated with similar hyperglycemia versus wild-type mice (350 vs. 385 mg/dl). Absence of SGLT1 attenuated upregulation of MD-NOS1 protein expression in diabetic Akita mice and in response to SGLT2 inhibition in nondiabetic mice. During SGLT2 inhibition in Akita mice, Sglt1−/− mice had likewise reduced blood glucose (200 vs. 300 mg/dl), associated with lesser MD-NOS1 expression, GFR, kidney weight, glomerular size, and albuminuria. Absence of Sglt1 in Akita mice increased systolic blood pressure, associated with suppressed renal renin mRNA expression. This may reflect fluid retention due to blunted hyperfiltration. SGLT2 inhibition prevented the blood pressure increase in Sglt1−/− Akita mice, possibly due to additive glucosuric/diuretic effects. The data indicate that SGLT1 contributes to diabetic hyperfiltration and limits diabetic hypertension. Potential mechanisms include its role in glucose-driven upregulation of MD-NOS1 expression. This pathway may increase GFR to maintain volume balance when enhanced MD glucose delivery indicates upstream saturation of SGLTs and thus hyperreabsorption.

scholarly journals SGLT2 inhibitor empagliflozin reduces renal growth and albuminuria in proportion to hyperglycemia and prevents glomerular hyperfiltration in diabetic Akita mice

2014 ◽  
Vol 306 (2) ◽  
pp. F194-F204 ◽  
Author(s):  
Volker Vallon ◽  
Maria Gerasimova ◽  
Michael A. Rose ◽  
Takahiro Masuda ◽  
Joseph Satriano ◽  
...  
Keyword(s):  
Gene Knockout ◽  
Sglt2 Inhibitor ◽  
Streptozotocin Diabetes ◽  
Glomerular Hyperfiltration ◽  
Vehicle Group ◽  
Renal Growth ◽  
Kidney Growth ◽  
Urinary Glucose ◽  
Sglt2 Inhibition ◽  
Akita Mice

Our previous work has shown that gene knockout of the sodium-glucose cotransporter SGLT2 modestly lowered blood glucose in streptozotocin-diabetic mice (BG; from 470 to 300 mg/dl) and prevented glomerular hyperfiltration but did not attenuate albuminuria or renal growth and inflammation. Here we determined effects of the SGLT2 inhibitor empagliflozin (300 mg/kg of diet for 15 wk; corresponding to 60–80 mg·kg−1·day−1) in type 1 diabetic Akita mice that, opposite to streptozotocin-diabetes, upregulate renal SGLT2 expression. Akita diabetes, empagliflozin, and Akita + empagliflozin similarly increased renal membrane SGLT2 expression (by 38–56%) and reduced the expression of SGLT1 (by 33–37%) vs. vehicle-treated wild-type controls (WT). The diabetes-induced changes in SGLT2/SGLT1 protein expression are expected to enhance the BG-lowering potential of SGLT2 inhibition, and empagliflozin strongly lowered BG in Akita (means of 187–237 vs. 517–535 mg/dl in vehicle group; 100–140 mg/dl in WT). Empagliflozin modestly reduced GFR in WT (250 vs. 306 μl/min) and completely prevented the diabetes-induced increase in glomerular filtration rate (GFR) (255 vs. 397 μl/min). Empagliflozin attenuated increases in kidney weight and urinary albumin/creatinine ratio in Akita in proportion to hyperglycemia. Empagliflozin did not increase urinary glucose/creatinine ratios in Akita, indicating the reduction in filtered glucose balanced the inhibition of glucose reabsorption. Empagliflozin attenuated/prevented the increase in systolic blood pressure, glomerular size, and molecular markers of kidney growth, inflammation, and gluconeogenesis in Akita. We propose that SGLT2 inhibition can lower GFR independent of reducing BG (consistent with the tubular hypothesis of diabetic glomerular hyperfiltration), while attenuation of albuminuria, kidney growth, and inflammation in the early diabetic kidney may mostly be secondary to lower BG.

Beneficial Effect of the SGLT2 Inhibitor Empagliflozin on Glucose Homeostasis and Cardiovascular Parameters in the Cohen Rosenthal Diabetic Hypertensive (CRDH) Rat

2018 ◽  
Vol 23 (4) ◽  
pp. 358-371 ◽  
Author(s):  
Firas Younis ◽  
Jonathan Leor ◽  
Zaid Abassi ◽  
Natalie Landa ◽  
Lea Rath ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Fasting Blood Glucose ◽  
Fatty Infiltration ◽  
Sglt2 Inhibitor ◽  
Preventive Treatment ◽  
Male Rats ◽  
Vehicle Group ◽  
Control Group ◽  
Model Assessment ◽  
Urinary Glucose

The effectiveness of empagliflozin (EMPA), a sodium glucose cotransporter type 2 inhibitor, on the kidney, pancreas, and heart was investigated in the Cohen Rosenthal diabetic hypertensive rat model (CRDH rat). Six-week-old CRDH male rats were fed a sugar diet (SD) and treated with the compound EMPA (group Drug/SD) or respective comparator with vehicle (group Veh/SD). A control group was fed a regular diet without treatment (group Veh/P). Preventive treatment with EMPA was measured during 4 months of follow-up. The treatment effect was evaluated according to results observed after 4 months in group Drug/SD when compared to those in group Veh/SD. Significant effect resulted in the following parameters: enhancement of urinary glucose excretion in association with diuresis; amelioration of postprandial hyperglycemia and fasting blood glucose levels; and decrease in calculated Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) as well as lower systolic and diastolic blood pressures. At the end of treatment, EMPA preserved nephrin integrity in the kidney, reduced proteinuria, and prevented diabetes-induced damage to glomerular diaphragm structure. In the pancreas, EMPA demonstrated an impressive decrease in fatty infiltration and atrophy. Blood pressure was significantly reduced in the EMPA-treated group (15 ± 5.1 mm Hg, P < .05) in contrast to the vehicle and control groups. Finally, compared to controls, EMPA significantly reduced left ventricle (LV) mass and LV systolic dilatation, according to 2-dimensional echocardiography. The importance of the study lies in demonstrating the efficacy of an antidiabetic drug with beneficial effects on blood pressure, weight, kidney, and pancreas and a positive effect on the heart.

Plasma and Renal Prorenin/Renin, Renin mRNA, and Blood Pressure in Dahl Salt-Sensitive and Salt-Resistant Rats

Hypertension ◽  
1996 ◽  
Vol 27 (5) ◽  
pp. 1121-1133 ◽  
Author(s):  
Wallace G. Campbell ◽  
Fuad Gahnem ◽  
Daniel F. Catanzaro ◽  
Gary D. James ◽  
Maria J. F. Camargo ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Renin Mrna

scholarly journals Development of osmotic vacuolization of proximal tubular epithelial cells following treatment with sodium-glucose transport protein 2 inhibitors in type II diabetes mellitus patients-3 case reports

2021 ◽  
Author(s):  
Shun Watanabe ◽  
Naoki Sawa ◽  
Hiroki Mizuno ◽  
Masayuki Yamanouchi ◽  
Tatsuya Suwabe ◽  
...  
Keyword(s):  
Serum Creatinine ◽  
Type Ii Diabetes ◽  
Sglt2 Inhibitor ◽  
Type Ii Diabetes Mellitus ◽  
Proximal Tubules ◽  
Type Ii ◽  
Tubular Epithelial Cells ◽  
Proximal Tubular Epithelial Cells ◽  
Proximal Tubular ◽  
Standard Weight

AbstractWe encountered 3 cases of acute kidney injury that occurred after treatment with a SGLT2 inhibitor. In case 1, serum creatinine increased from 1.65 to 3.0 mg/dL, in case 2, serum creatinine increased from 1.03 to 1.21 mg/dL, and in case 3, serum creatinine increased from 0.8 to 1.1 mg/dL. Renal biopsy showed isometric vacuolization on tubules, that was completely negative for Periodic acid-Schiff (PAS) stain in case 1, and was partially negative for PAS stain in case 2 and 3, consistent with osmotic vacuolization. Immunohistochemical analysis showed positive staining for CD138 and CD10 indicating the proximal tubules in the vacuolar lesions. 3 patients were obese with body mass index of more than 30, and showed an increase in serum renin. In conclusion, in type II diabetes mellitus (T2DM), individuals that remain within their standard weight range, SGLT2 inhibitor treatment does not result in osmotic vacuolization of proximal tubular epithelial cells and AKI. However, treatment with a SGLT2 inhibitor may cause damage of the proximal tubules resulting in AKI in T2DM individuals who do not remain within their standard weight range, due to an overdose lavage of sugar in the urine and dehydration.

scholarly journals Tubular Deficiency of Heterogeneous Nuclear Ribonucleoprotein F Elevates Systolic Blood Pressure and Induces Glycosuria in Mice

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Chao-Sheng Lo ◽  
Kana N. Miyata ◽  
Shuiling Zhao ◽  
Anindya Ghosh ◽  
Shiao-Ying Chang ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Interstitial Fibrosis ◽  
Sglt2 Inhibitor ◽  
Systemic Hypertension ◽  
Male And Female ◽  
Heterogeneous Nuclear Ribonucleoprotein ◽  
Elevated Systolic Blood Pressure ◽  
Nuclear Ribonucleoprotein ◽  
Heterogeneous Nuclear Ribonucleoprotein F

Abstract We reported previously that overexpression of heterogeneous nuclear ribonucleoprotein F (Hnrnpf) in renal proximal tubular cells (RPTCs) suppresses angiotensinogen (Agt) expression, and attenuates systemic hypertension and renal injury in diabetic Hnrnpf-transgenic (Tg) mice. We thus hypothesized that deletion of Hnrnpf in the renal proximal tubules (RPT) of mice would worsen systemic hypertension and kidney injury, perhaps revealing novel mechanism(s). Tubule-specific Hnrnpf knockout (KO) mice were generated by crossbreeding Pax8-Cre mice with floxed Hnrnpf mice on a C57BL/6 background. Both male and female KO mice exhibited elevated systolic blood pressure, increased urinary albumin/creatinine ratio, tubulo-interstitial fibrosis and glycosuria without changes in blood glucose or glomerular filtration rate compared with control littermates. However, glycosuria disappeared in male KO mice at the age of 12 weeks, while female KO mice had persistent glycosuria. Agt expression was elevated, whereas sodium-glucose co-transporter 2 (Sglt2) expression was down-regulated in RPTs of both male and female KO mice as compared to control littermates. In vitro, KO of HNRNPF in human RPTCs (HK-2) by CRISPR gRNA up-regulated AGT and down-regulated SGLT2 expression. The Sglt2 inhibitor canagliflozin treatment had no effect on Agt and Sglt2 expression in HK-2 and in RPTCs of wild-type mice but induced glycosuria. Our results demonstrate that Hnrnpf plays a role in the development of hypertension and glycosuria through modulation of renal Agt and Sglt2 expression in mice, respectively.

scholarly journals Increase in SGLT1-mediated transport explains renal glucose reabsorption during genetic and pharmacological SGLT2 inhibition in euglycemia

2014 ◽  
Vol 306 (2) ◽  
pp. F188-F193 ◽  
Author(s):  
Timo Rieg ◽  
Takahiro Masuda ◽  
Maria Gerasimova ◽  
Eric Mayoux ◽  
Kenneth Platt ◽  
...  
Keyword(s):  
Knockout Mice ◽  
Plasma Concentrations ◽  
Sglt2 Inhibitor ◽  
Double Knockout ◽  
Glucose Reabsorption ◽  
Urinary Glucose ◽  
Sglt2 Inhibition ◽  
Renal Glucose Reabsorption ◽  
Glucose Excretion ◽  
Free Plasma

In the kidney, the sodium-glucose cotransporters SGLT2 and SGLT1 are thought to account for >90 and ∼3% of fractional glucose reabsorption (FGR), respectively. However, euglycemic humans treated with an SGLT2 inhibitor maintain an FGR of 40–50%, mimicking values in Sglt2 knockout mice. Here, we show that oral gavage with a selective SGLT2 inhibitor (SGLT2-I) dose dependently increased urinary glucose excretion (UGE) in wild-type (WT) mice. The dose-response curve was shifted leftward and the maximum response doubled in Sglt1 knockout (Sglt1−/−) mice. Treatment in diet with the SGLT2-I for 3 wk maintained 1.5- to 2-fold higher urine glucose/creatinine ratios in Sglt1−/− vs. WT mice, associated with a temporarily greater reduction in blood glucose in Sglt1−/− vs. WT after 24 h (−33 vs. −11%). Subsequent inulin clearance studies under anesthesia revealed free plasma concentrations of the SGLT2-I (corresponding to early proximal concentration) close to the reported IC50 for SGLT2 in mice, which were associated with FGR of 64 ± 2% in WT and 17 ± 2% in Sglt1−/−. Additional intraperitoneal application of the SGLT2-I (maximum effective dose in metabolic cages) increased free plasma concentrations ∼10-fold and reduced FGR to 44 ± 3% in WT and to −1 ± 3% in Sglt1−/−. The absence of renal glucose reabsorption was confirmed in male and female Sglt1/Sglt2 double knockout mice. In conclusion, SGLT2 and SGLT1 account for renal glucose reabsorption in euglycemia, with 97 and 3% being reabsorbed by SGLT2 and SGLT1, respectively. When SGLT2 is fully inhibited by SGLT2-I, the increase in SGLT1-mediated glucose reabsorption explains why only 50–60% of filtered glucose is excreted.

scholarly journals Harnessing basic and clinic tools to evaluate SGLT2 inhibitor nephrotoxicity

2017 ◽  
Vol 313 (4) ◽  
pp. F951-F954 ◽  
Author(s):  
Danielle L. Saly ◽  
Mark A. Perazella
Keyword(s):  
Early Stage ◽  
Functional Decline ◽  
Healthcare Providers ◽  
Sglt2 Inhibitor ◽  
Kidney Injury ◽  
Renin Angiotensin System ◽  
Sglt2 Inhibitors ◽  
Diabetic Patients ◽  
Chip Technology ◽  
Urinary Glucose

Sodium-glucose cotransporter-2 (SGLT2) inhibitors are a new class of medications that target the transporter that reabsorbs ~90% of glucose in the S1 segment of the proximal convoluted tubule. As a result, SGLT2 inhibition increases urinary glucose excretion, effectively lowering plasma glucose levels. In addition to reducing hemoglobin A1c levels, these drugs also lower body weight, blood pressure, and uric acid levels in Type 2 diabetes mellitus (T2DM) patients. Importantly, empagliflozin has been observed to slow progression of kidney disease and reduce dialysis requirements in T2DM patients. However, the Food and Drug Administration (FDA) Adverse Events Reporting System (FAERS) has collected over 100 cases of acute kidney injury (AKI) for canagloflozin and dapagliflozin since their approval. Of the 101 patients, 96 required hospitalization, 22 required intensive care unit admission, and 15 underwent hemodialysis. The FDA now requires that AKI be listed as a potential side effect of the SGLT2 inhibitors along with cautious prescription of these drugs with other medications, such as renin-angiotensin-system antagonists, diuretics, and NSAIDs. It is unclear, however, whether this FAERS reported “AKI” actually represents structural kidney injury, as randomized, controlled trials of these drugs do not describe AKI as an adverse event despite coprescription with RAS blockers and diuretics. As a result of this FDA warning, diabetic patients with early-stage CKD may not be prescribed an SGLT2 inhibitor for fear of AKI. Thus, it is imperative to ascertain whether the reported AKI represents true structural kidney injury or a functional decline in glomerular filtration rate. We propose using readily available clinical tools with experimental biomarkers of kidney injury and kidney-on-a-chip technology to resolve this question and provide solid evidence about the AKI risk of these drugs for healthcare providers.

Abstract 101: Tissue-specific Deletion of Collectrin in the Proximal Tubular Epithelium Increases Arterial Pressure and Augments Salt-sensitivity

Hypertension ◽  
2017 ◽  
Vol 70 (suppl_1) ◽  
Author(s):  
Sylvia Cechova ◽  
Pei-Lun Chu ◽  
Joseph C Gigliotti ◽  
Fan Chan ◽  
Thu H Le
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Renal Blood Flow ◽  
Collecting Duct ◽  
Critical Role ◽  
Specific Effect ◽  
Salt Sensitivity ◽  
Kidney Cortex ◽  
Mrna Levels ◽  
Proximal Tubular

Background: Collectrin ( Tmem27 ) is a key regulator of blood pressure (BP) and modulator of the bioavailability of nitric oxide (NO) and superoxide. It is highly expressed in the kidney in the proximal tubule (PT), collecting duct, and throughout the vascular endothelium. We reported that collectrin plays a critical role as a chaperone for the reabsorption of all amino acids (AAs) in the PT, and for the uptake of the cationic AA L-arginine (L-Arg) in endothelial cells. Global collectrin knockout ( Tmem27 Y/- ) mice display baseline hypertension (HTN), augmented salt-sensitive hypertension (SSH), and decreased renal blood flow. Objective and Methods: To determine the PT-specific effect of collectrin on BP homeostasis and salt sensitivity, we used the Cre -loxP approach and PEPCK-Cre to generate a mouse line lacking collectrin specifically in the PT-- PEPCK-Cre + Tmem27 Y/Flox mice. PEPCK-Cre - Tmem27 Y/Flox mice were used as control. Radiotelemetry was used to measure BP for 2 weeks at baseline and 2 weeks on high salt diet (HSD). Renal blood flow at baseline and on HSD was measured using contrast enhanced ultrasound in the same mice. Results: Successful deletion of collectrin in the PT was confirmed by assessing mRNA levels using real-time RT-PCR, immunohistochemistry staining of renal tissues using anti-collectrin antibody, and quantitation of protein from kidney cortex by Western analysis. Compared to control PEPCK-Cre - Tmem27 Y/Flox mice (n=6), PEPCK-Cre + Tmem27 Y/Flox mice (n=6) displayed significantly higher systolic BP (SBP) at baseline (120.0 ± 2.5 vs 131.6 ± 2.9 mm Hg; p = 0.014) and after HSD (135.3 ± 2.6 vs 151.5 ± 5.2 mm Hg; p = 0.019). Renal blood flow was not different between groups, at baseline nor after HSD. Conclusion: Collectrin in the PT plays an important role in blood pressure homeostasis and response to sodium intake, independent of renal blood flow. Increasing proximal tubular collectrin activity may be a novel therapeutic strategy for the treatment of hypertension and salt-sensitivity.

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