J.Jpn. Surg. Soc.. 60(12): 1911-1922, 1960

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THE EFFECT OF NITROMIN ON ENDOGENOUS DEHYDROGENASE ACTIVITY OF NITROMIN SUSCEPTIBLE AND RESISTANT STRAINS OF YOSHIDA ASCITES SARCOMA

Nitromin Susceptible original strain of Yoshida Ascites Sarcoma and Nitromin resistant strain of Yoshida Ascites Sarcoma, which acquired resistancy by succesive administration, are used as a material to clarify the characteristics of drug resistancy. Both strains are morphologically same in size, in form and consist of free single cells in rat ascites. Endogenous Dehydrogenase Activity of the tumor cells is determined by triphenyltetrazolium chloride (TTC) and methylene blue (MB). 3 methods are used.
1) TTC without evacuation, 2) TTC with evacuation in Thumberg tube, 3) TTC ＆ MB with evacuation in Thumberg tube.
(I) Determination of the suitable conditions for measurement: Tumor cell numbers neccessary for measurement (Fig. 3), Suitable incubation time (Fig. 4), Concentration of the reaction system in pH 7.2, 0.1 M Phosphate Buffer (Fig. 5), Suitable pH for measurement (Fig. 6), TTC concentration (Fig. 7).
(II) Comparison of the 3 methods, in regard to the effect of Nitromin or Nitrogen Mustard N-oxide upon the Endogenous Dehydrogenase Activity (Fig. 8, Fig. 9, Fig. 10).
The difference between the effect of Nitromin on the susceptible and resistant strains in the presence of TTC and MB is striking.
(III) Comparison of the effect of Nitromin upon both strains, after cell disruption with desintegrator: After cell disruption, the susceptible group retains a greater degree of sensitivity than the resistant group in the presence of TTC ＆ MB (Fig. 11).
The difference of the susceptible and resistant cells seems not to be dependent upon the permeability of the cell membrane. Both tumor cells seem to have their own biochemical and physicochemical properties in protoplasm.

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