Oxygen consumption and oxygen diffusion properties of multicellular spheroids from two different cell lines.

A recently developed method for evaluating pO2 gradients in multicellular spheroids enabled the determination of the volume-related O2 consumption rate Q and of Krogh' diffusion constant KS in EMT6- and in V79-spheroids on the basis of pO2 measurements with microelectrodes. In addition, estimates for the weight-related water content W, for the O2 diffusivity D and for the O2 solubility in spheroids could be derived from KS. The results show that O2 consumption and O2 diffusion properties of multicellular spheroids are greatly influenced by the cell line chosen. On the average, Q is larger in V79-spheroids than in EMT6-spheroids, whereas KS, W, D and alpha are lower in V79-spheroids than in EMT6-spheroids. There is a decrease in Q with increasing spheroid diameter in either spheroid type, and Q in both spheroid types is lower than the respective value in single cells. Using the data obtained, theoretical pO2-profiles can be calculated that are in good agreement with the measured steady state pO2 distribution in all spheroids investigated.