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Dietary Fructose Enhances the Ability of Low Concentrations of Angiotensin II to Stimulate Proximal Tubule Na⁺ Reabsorption.

Dietary Fructose Enhances the Ability of Low Concentrations of Angiotensin II to Stimulate Proximal Tubule Na⁺ Reabsorption.
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Gonzalez-Vicente A, Cabral PD, Hong NJ, Asirwatham J, Yang N, Berthiaume JM, Dominici FP, Garvin JL,


Gonzalez-Vicente A, Cabral PD, Hong NJ, Asirwatham J, Yang N, Berthiaume JM, Dominici FP, Garvin JL, (click to view)

Gonzalez-Vicente A, Cabral PD, Hong NJ, Asirwatham J, Yang N, Berthiaume JM, Dominici FP, Garvin JL,

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Nutrients 2017 08 169(8) pii E885
Abstract

Fructose-enriched diets cause salt-sensitive hypertension. Proximal tubules (PTs) reabsorb 70% of the water and salt filtered through the glomerulus. Angiotensin II (Ang II) regulates this process. Normally, dietary salt reduces Ang II allowing the kidney to excrete more salt, thereby preventing hypertension. We hypothesized that fructose-enriched diets enhance the ability of low concentrations of Ang II to stimulate PT transport. We measured the effects of a low concentration of Ang II (10(-12) mol/L) on transport-related oxygen consumption (QO₂), and Na/K-ATPase and Na/H-exchange (NHE) activities and expression in PTs from rats consuming tap water (Control) or 20% fructose (FRUC). In FRUC-treated PTs, Ang II increased QO₂ by 14.9 ± 1.3 nmol/mg/min (p < 0.01) but had no effect in Controls. FRUC elevated NHE3 expression by 19 ± 3% (p < 0.004) but not Na/K-ATPase expression. Ang II stimulated NHE activity in FRUC PT (Δ + 0.7 ± 0.1 Arbitrary Fluorescent units (AFU)/s, p < 0.01) but not in Controls. Na/K-ATPase activity was not affected. The PKC inhibitor Gö6976 blocked the ability of FRUC to augment the actions of Ang II. FRUC did not alter the inhibitory effect of dopamine on NHE activity. We conclude that dietary fructose increases the ability of low concentrations of Ang II to stimulate PT Na reabsorption via effects on NHE.

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