Effects of Dietary Potassium on Expression of AT1R and ATRAP

Previous studies have shown that potassium depletion enhances AT1 receptor density in the apical membrane, the basal membrane and nuclei of proximal tubular cells. The purpose of this study was to analyze the effect of high K+ intake and K+ depletion on Angiotensin II receptor (AT1R) and ATRAP (AT1R receptor-associated protein) expression on kidney cortex. Wistar rats were divided into three groups: 1) normal K+, 2) high K+ (9%) and 3) K+ depletion. The cortical portion was analysed by “Western/imunobloting” with anti-AT1R and anti-ATRAP antibodies. ATRAP and AT1R total mRNA were quantified by real-time PCR. using total proteins extract, we observed an increase in AT1R expression of 119% in the overload group and 280% in the K+-depleted group. ATRAP expression was increased by 82% in K+-depleted group, whereas in K+ overload group there were no changes in ATRAP expression. The ATRAP/AT1R expression ratio decreased 38% in overload and 52% in depleted models. In total membrane fractions it was observed an increase of 82% in AT1R and 128% increase in ATRAP expression in depletion model, as ATRAP/AT1R expression ratio was not affected. The results of real-time analysis showed a decrease of 9% in AT1R and 4% in ATRAP in the K+ overload group. In the K+-depleted group, AT1R decreased 36% and ATRAP 20%. In conclusion, we showed that both, high K+ intake or K+ depletion significantly modifies AT1R and ATRAP protein expression and mRNA abundance, except for ATRAP protein abundance in the overloaded model. Besides, based in our results, we postulate that treatment of animals for 7 days with this dietary may influence the post-translational modifications in AT1R and ATRAP proteins, since we observed an increase in protein expression with reduced mRNA abundance of these proteins.