Amiloride interferes with platelet-activating factor-induced respiratory burst and MMP-9 release in bovine neutrophils independent of Na+/FH+ exchanger 1

Cytoplasmic pH homeostasis is required for an appropriate response in polymorphonuclear neutrophils (PMNs). In these cells, chemotaxis and reactive oxygen species (ROS) production are reduced by the use of Na+/H+ exchanger (NHE-1) inhibitors, but these results are mainly obtained using amiloride, a non-selective NHE-1 inhibitor. In bovine PMNs, the role of NHE-1 in functional responses has not been confirmed yet. The aim of this study was to determine the role of NHE-1 using amiloride and zoniporide in pH regulation, ROS production, matrix metalloproteinase 9 (MMP-9) release and calcium flux in bovine PMNs induced by the platelet activation factor (PAF), additionally we evaluated the presence of NHE-1 and NHE-2 mRNA Our data show the presence only of NHE-1 but not NHE-2 in bovine PMNs. Amiloride or zoniporide inhibited the intracellular alkalization induced by PAP without affecting calcium flux. Amiloride diminished ROS production and MMP-9 release, while zoniporide enhanced ROS production without change the MMP-9 release induced by PAF. Our work led us to conclude that changes in intracellular pH induced by PAF are regulated by NHE-1 in bovine neutrophils, but the effects of amiloride on ROS production and MMP-9 release induced by PAF are not NHE-1 dependent.