Investigation on the radiomodifying effect of procain hydrochloride on the multicellular spheroid model

On multicellular spheroids from V-79-4 cells with a relatively high portion of hypoxic cells the radiomodifying effect of procain was investigated by means of the measured quantities relative increase in volume and formation of outgrowth. The formation of outgrowth and recovery, respectively, of the spheroids is directly correlated with the capability of survival. As the recovery originates from cells being hypoxic during irradiation and capable of migration a smaller formation of outgrowth after irradiation would speak in favor of a hypoxically sensibilizing influence by procain. Following 20, 30, and 40 Gy of single cesium gamma irradiation and treatment of each spheroid with 0.1 ml of 1 mM procain hydrochloride a somewhat delayed formation of outgrowth in the procain-treated and irradiated groups was observed with nearly the same frequency of outgrowths at the end of the observation time in both groups. The hypoxically radiosensibilizing effect described by George, Shenoy et al. could not be confirmed on multicellular spheroids. (author)