WST-assay data reveal a pH dependence of the mitochondrial succinate reductase in osteoblast-like cells

The data presented in this article are related to the research article entitled "Increased osteoblast viability at alkaline pH in vitro provides a new perspective on bone regeneration" (doi: 10.1016/j.bbrep.2017.02.001; (Galow et al., 2017) [1]). The water soluble tetrazolium (WST) proliferation assay detects the metabolic activity of the respiratory chain of cultured cells. The assay is based on changes in the light absorbance resulting from the metabolism of WST-1 into formazane by mitochondrial succinate reductase. We present data of three different tests that were carried out to check whether WST assay readouts are pH-dependent. In a first test, a possible pH effect on the photometric measurements, for example by shifting the absorbance spectrum of the pH indicator of the cell culture medium, was excluded. Because the second test revealed a significant pH-dependence of the activity of the mitochondrial succinate reductase, a third long-term test was conducted to analyze possible changes of the pH dependence over time. The higher absorbance per one million cells at alkaline pH, which was approximately four-fold at pH 8.4 compared to the pH-7.4 reference on day one decayed gradually, with the pH-differences equilibrating over six days.