High Salt Enhances Reactive Oxygen Species and Angiotensin II Contractions of Glomerular Afferent Arterioles From Mice With Reduced Renal Mass

High salt, Ang II (angiotensin II), and reactive oxygen species enhance progression of chronic kidney disease. We tested the hypothesis that a high salt intake generates specific reactive oxygen species to enhance Ang II contractions of afferent arterioles from mice with reduced renal mass (RRM). C57BL/6 mice were subjected to surgical RRM or sham operations and received 6% or 0.4% NaCl salt diet for 3 months. Ang II contractions were measured in perfused afferent arterioles and superoxide (O 2 − ) and hydrogen peroxide (H 2 O 2 ) by fluorescence microscopy. RRM enhanced the afferent arteriolar gene expression for p47 phox and neutrophil oxidase (NOX) 2 and high salt intake in RRM mice enhanced gene expression for angiotensin type 1 receptors, POLDIP2 and NOX4 and reduced catalase. High salt in mice with RRM enhanced arteriolar O 2 − and H 2 O 2 generation and maximal contractions to Ang II (10 –6 mol/L) that were dependent on O 2 − because they were prevented by gene deletion of p47 phox and on H 2 O 2 because they were prevented by transgenic smooth muscle cell expression of catalase (tg CAT-SMC ) and POLDIP2 gene deletion. Three months of tempol normalized arteriolar reactive oxygen species and Ang II contractions. However, arteriolar contractions to lower concentrations of Ang II (10 –8 to 10 –11 mol/L) were paradoxically inhibited by H 2 O 2 and POLDIP2. In conclusion, both O 2 − from p47 phox /NOX2 and H 2 O 2 from NOX4/POLDIP2 enhance maximal arteriolar Ang II contractions from RRM mice during high salt, but H 2 O 2 and NOX4/POLDIP2 reduce the sensitivity to lower concentrations of Ang II by >100-fold. Tempol prevents all of these changes in function.