The NADPH oxidase is involved in volume‐sensitive ROS production in NIH3T3 mouse fibroblasts

It has previously been shown that reactive oxygen species (ROS) are produced by NIH3T3 cells following hypotonic exposure and that they modulate the concomitant swelling‐induced release of organic osmolytes (JMB 192, –32, 2003). Here we demonstrate that NIH3T3 cells express the NADPH oxidase subcomponents p47 phox , p67 phox and the gp91 phox analogue NOX4. Furthermore, the swelling‐induced ROS production is significant increased following a reduction in the extracellular osmolarity by approximately 35 mOsm and it is sensitive to the NADPH‐oxidase inhibitor diphenylene iodonium chloride, a conventional protein kinase C (PKC) inhibitor GÖ6976, but insensitive to the nitrogen oxide synthetase inhibitor L‐NAME. As p47 phox activation involves PKC mediated phosphorylation we suggest that the NADPH oxidase is involved in volume‐sensitive ROS production in NIH3T3 mouse fibroblasts, that the oxidase has a volume set‐point and that its activity is modulated by a conventional PKC.