Biophysical aspects of the integrated combination of cytostatic drugs with radiotherapy. Part 3: In vivo investigations on murine C3H mammary adenocarcinoma treated with cis-platinum, adriamycin, epirubicin, activated cyclophosphamide, activated isophosphamide and irradiation with 10 MeV electrons--verification of the therapeutic results with 31P-NMR spectroscopy.

Radiobiological data referring to in vitro cell cultures proved to be adequate for the determination of an optimum sequence between drug incubation and consecutive irradiation, if the intracellular pH was subjected to accurate controls. An extension of the comparative study to the in vivo model of murine C3H mammary adenocarcinoma yielded synergistic effects, if the animals were treated with 10 MeV electrons and one of the drugs: cis-platinum, adriamycin, epirubicin, activated cyclophosphamide, activated isophosphamide. For comparative purpose the survey of the therapeutic results during and after finishing of the schedules was performed with 31P-NMR spectroscopy, radiometry (3H-thymidine) and a scanning system using 100 pH sensor microelectrodes. Although most extensive with regard to measurement technique, the latter method provided an accurate local pH distribution of a tumor tissue, while 31P only yielded the global pH-value (average).