Effect of protein kinase A (PKA) on the expression and activity of Na+/H+ exchanger isoform 3 (NHE3) in a model of ischemia and reperfusion.

• Grant number: 25/03043-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2025
• End date: November 30, 2025
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Maria Oliveira de Souza
• Grantee: Natalia Marques Guilherme
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Acute kidney injury (AKI) induced by ischemia/reperfusion (IR) contributes to a high rate of morbidity and mortality in a wide range of injuries. In this condition, renal tubular cells suffer severe damage that can interfere with the body's homeostasis, including sodium and water balance, since lesions in the tubular epithelia prevent the proper function of sodium transporters such as the Na+/H+ exchanger, isoform 3 (NHE3), the Na+:K+:2Cl- cotransporter (NKCC2), the Na+:Cl- cotransporter (NCC), Na+ channels (ENACs) and the Na+/K+/ATPase. However, when it comes to IR, most studies have focused on the function of the proximal tubule. Thus, our hypothesis is that IR may also induce injury in the thick ascending limb of the loop of Henle, which results in changes in the expression and activity of NHE3. The aim of this study is to investigate the relationship between thick loop injury and NHE3 activity, observing the contribution of the PKA signaling pathway. For this purpose, in vivo and in vitro models of IR will be used. Eight-week-old C57BL/6J mice subjected to bilateral renal IR will be compared to the sham group. TKPTS cells (mouse proximal tubular cell line) will be subjected to IR by treatment with antimycin A (5 µM) and/or H-89 (1 µM, PKA inhibitor) and compared to the respective controls. For this purpose, ischemia and reperfusion techniques, western blotting, trypan blue staining, immunofluorescence and intracellular pH measurements will be used.