Release of acidic components by prosthesis loosening fibroblasts (PLFs). (a) and (b) Cytosensor measurement of PLFs stimulated with tumour necrosis factor (TNF)-α (1, 10 and 300 ng/ml) revealed the release of acidic components, with maximal pericellular acidification (rmax/req) of 15% at 10 ng/ml TNF-α (A). Recording of the time curve with 10 ng/ml TNF-α showed a maximal acidification 15 min after the influx of TNF-α was started (b). (c) Incubation of PLFs with the ATPase inhibitors amiloride and bafilomycin A1 at different concentrations decreased the pericellular acidification by a maximum of 32% with amiloride and 11% with bafilomycin A1. (d) Inhibition of H + release by amiloride was recorded after 3 min and remained stable for the total measuring time of 45 min. Pericellular pH returned to the initial values shortly after the perfusion of amiloride was terminated. (e) The specific v-ATPase inhibitor bafilomycin A1 at concentrations of 10-6 mol/l showed a clear effect shortly after its addition, and the H+ secretion remained low even after discontinuation of bafilomycin A1 infusion.
Pap et al. Arthritis Res Ther 2003 5:R163-R173 doi:10.1186/ar752