[Measurements of ion concentrations with microelectrodes on vital tissue sections of human breast cancer].

The transmembrane potential (TMP) was described as a rapidly reacting and sensitive indicator for a great number of cell functions. The present paper reports on the measurement of ion concentration (IC) on vital microscopically controlled human mammary tissue slices. Satisfactory results have been achieved with changed on-light observation in comparison to other customary methods. Whereas a cytoxic effect has been observed with all treatments by means of 3H-thymidine uptake, IC-measurements showed only effects with Daunoblastin or distilled water in 4 out of 16 experiments. The effect of Daunoblastin measured by ion concentrations seems to be better visible if the tissue culture medium is exchanged by physiological NaCl-solution (0.9%). Nevertheless the described method cannot be recommended for drug sensitivity testing of human mammary carcinomas in organ culture.