EPR oximetry: reduction of cell respiration by vinblastine.

Influence of vinblastine (VLB) on the rate of oxygen uptake by HeLa cells was studied using the electron paramagnetic resonance (EPR) method. A suspension of cells was labelled with spin probe 15N PDT. Broadening of the EPR spectrum line widths in the presence of O2 was used to measure its concentration throughout the sample. VLB decreased the rate of O2 consumption, but did not influence the viability of cells at the concentration used (1 ng/ml). In addition, intracellular O2 concentration was measured using a paramagnetic broadening agent CrOX. No significant difference in the intracellular O2 concentration with respect to the extracellular was observed neither in VLB treated nor in untreated cells.