SO039BETA3-ADRENORECEPTOR AS A NEW PLAYER IN SYMPATHETIC REGULATION OF THE ACID-BASE HOMEOSTASIS IN THE KIDNEY. (6th June 2020)

• Record Type: Journal Article
• Authors: Milano, Serena; Gerbino, Andrea; Carmosino, Monica; Svelto, Maria; Procino, Giuseppe
• Is Part Of: Nephrology dialysis transplantation. Volume 35(2020)Supplement 3
• Publication Date: 2020-06-06
• Subjects: Nephrology -- Periodicals; Hemodialysis -- Periodicals; Kidneys -- Transplantation -- Periodicals; Hemodialysis; Kidneys -- Transplantation; Nephrology; Periodicals; 616.61
• DOI: 10.1093/ndt/gfaa139.SO039
• Languages: English
• ISSNs: 0931-0509

Abstract

Abstract: Background and Aims: Sympathetic nervous system has a key role in the regulation of renal function. We previously showed that, in mouse, the β3 -adrenoreceptor (β3 -AR) localizes in most of the nephron segments and its selective agonism promotes a potent antidiuretic effect. Here, we evaluate the expression of β3 -AR in kidney intercalated cells (ICs) which are associated with the regulation of acid-base homeostasis in distal segments of the kidney tubule. The aim of this study is to investigate whether the β3 -AR might play a role in the acid-base homeostasis operated by the kidney. Method: The β3 -AR expression in mouse kidney ICs was investigated by confocal microscopy. Wild type (wt) and β3 -AR knock-out (ko) mice were used to study the role of β3 -AR in the renal acid-base homeostasis. Mouse urine were collected using metabolic cages and pH was measured. Immunofluorescence and Western blotting experiments were performed to evaluate the localization and the abundance of renal H + -ATPase in wt and β3 -AR ko mice. Kidney cells expressing human β3 -AR (M1-β3 -AR) and endogenous H + -ATPase were used to investigate the possible effects of β3 -AR stimulation on the activity/localization of H + -ATPase. Live imaging experiments using the pH-sensitive dye BCECF were carried out to determine intracellular pH and assess H + -ATPase activity. Immunofluorescence experiments were performed to reveal the effects of β3 -AR activation on H + -ATPase localization. Results: Co-localization study of β3 -AR with either H + -ATPase or Cl − /HCO3− exchanger pendrin in mouse kidney showed that β3 -AR is expressed in H + -secreting type A, in HCO3 — secreting type B, and in non-A non-B ICs. The urine pH of β3 -AR ko mice was significantly higher compared with wt mice. In line with these results, localization and expression analysis showed that renal H + -ATPase significantly decreased in β3 -AR ko mice compared to wt mice, supporting the idea that H + secretion is partially blunted in these animals. Of note, exposure of M1-β3 -AR cells to a selective β3 -AR agonist induced a 2.5 fold increase of H + -ATPase activity compared to resting cells and this effect was prevented by a selective β3 -AR antagonist or by the H + -ATPase inhibitor bafilomycin. Moreover, β3 -AR agonism enhanced H + -ATPase apical expression in M1-β3 -AR cells. In addition, the PKA inhibitor H89 abolished the stimulatory effect of β3 -AR agonism, demonstrating the involvement of the cAMP/PKA pathway. Conclusion: The present data suggest that modulation of H + -ATPase activity in renal ICs by endogenous β3 -AR agonists may play an addition physiological role in hormonal control of renal acid-base homeostasis.