The Thiazide-Sensitive Co-Transporter Promotes the Development of Sodium Retention in Mice with Diet-Induced Obesity

Abstract

Background/Aims: Intravascular volume expansion due to sodium retention is involved in the pathogenesis of obesity-related hypertension. Institution of high fat diet (HFD) feeding leads to an initial state of positive sodium balance due to enhanced tubular reabsorption of sodium, but which tubular sodium transporters are responsible for this remains undefined. Methods: C57/Bl6 mice were fed control or HFD for 3 weeks. Blood pressures were recorded by tail cuff method. Sodium transporter expression and phosphorylation were determined by Western blotting. In vivo activity of NCC was determined using natriuretic responses to hydrochlorothiazide. Expression of NCC mRNA was determined using qPCR. Results: At 3 weeks HFD mice had significant weight gains compared to control mice, but blood pressures were not yet elevated. There were no changes in expression or phosphorylation of the bumetanide-sensitive cotransporter, NKCC2, or in expression of subunits of the amiloride-sensitive ion channel, ENaC. However, there were significant increases in mRNA and protein expression of the thiazide-sensitive co-transporter, NCC, in kidneys from HFD mice. Consistent with this, HFD mice had increased in vivo activity of NCC. Conclusions: Increased expression of NCC promotes the sodium loading response to institution of HFD feeding before onset of hypertension.

Elevated aldosterone and blood pressure in a mouse model of familial hyperaldosteronism with ClC-2 mutation

“…After reverse transcription of RNA using Quantitect RT Kit (Qiagen), Taqman gene expression assays (Applied Biosystems) for Gapdh (Mm99999915_g1, housekeeping gene), Cyp11b2 (Mm00515624_m1) and Clcn2 (Mm01344259_m1) were performed for adrenal samples. Gapdh (primers 5′-TGTAGACCATGTAGTTGAGGTCA-3′ and 5′-AGGTCGGTGTGAACGGATTTG-3′), Ren1 (5′-TCTGGGCACTCTTGTTGCTC-3′ and 5′-GGGGGAGGTAAGATTGGTCAA-3′), Slc13a2 (5′-CGAGAGTAATCCAGCAGTA-3′ and 5′-ATGAAGAGATTAACAAGAACAGAA-3′) 54 and Sgk1 (5′-ATGCAGTAAACCAGCCGGT-3′ and 5′-TGATCCATCTTCGTACCCGT-3′) were amplified from kidney cDNA using Power SYBR Green PCR Master Mix (Applied Biosystems). Gene expression was evaluated relative to Gapdh , and mean ΔCT of WT controls and expressed as 2 ΔΔCt (fold change).…”

High fat diet confers vascular hyper-contractility against angiotensin II through upregulation of MLCK and CPI-17

“…RAAS plays a critical role in the elevation of blood pressure via regulating vascular contractility and blood volume [4]. High fat diet (HFD)-induced hypertension is established animal model to study renal and cardiovascular factors for the obesity-related hypertension [5678]. There are lines of evidence that inhibition of Ang II prevents HFD-induced hypertension [9].…”

11β-Hydroxysteroid Dehydrogenases and Hypertension in the Metabolic Syndrome

“…High-fat feeding to mice recapitulates key features of metabolic syndrome. Impaired sodium excretion and salt-sensitive hypertension reflect activation of furosemide-sensitive NKCC2 [ 77 ] and NCC [ 78 ], rather than ENaC [ 79 ].…”