Studies on succinate-tetrazolium reductase systems IV. Histochemical aspects

Abstract

Summary A study has been made concerning the composition of three different succinate-tetrazolium reductase systems present in 6-μ sections of rat liver. The tetrazolium salts studied were C,N -diphenyl- N' -4,5-dimethylthiazol-2-yl tetrazolium bromide (MTT, with and without the addition of CoCl 2 ) and nitro-blue tetrazolium. In the case of MTT, both in the presence and in the absence of added Co 2+ , the succinate-MTT reductase system showed close similarities to the system previously studied in tissue specimens. Co 2+ produced a marked inhibition of the overall reaction in sections though not to such an extent as found in suspensions. It is concluded that the routine histochemical procedure using MTT demonstrates a similar sequence of reactions to that occurring in liver homogenates where MTT is reduced via two main interactions with the respiratory chain. In the case of nitro-blue tetrazolium, a similar close resemblance was found between the results obtained in this study with frozen sections and those previously obtained with suspensions.