Observations on the use of nitro blue tetrazolium in the detection of early myocardial changes.

Abstract

Reserpine-induced cardiomyopathy in guineapigs was studied by means of histochemical dehydrogenase reactions using succinate as substrate and tetrazolium salts as electron acceptors. Succinate: Nitro Blue tetrazolium oxidoreductase activity in the ventricular muscle of reserpine-treated animals was localized cytochemically in a blue ‘granular’ pattern instead of the purple ‘myofibrillar’ pattern typical of the normal myocardium. A series of experiments designed to investigate their mechanism showed that the blue ‘granular’ pattern is a physicochemical sequel secondary to the fatty deposition in the disordered myocardial cells and, moreover, the preferential deposition of the blue dinitroformazan is not indicative of augmented succinate: Nitro Blue tetrazolium oxidoreductase activity. It is concluded that the histochemical reaction for this enzyme is a very sensitive index of myocardial alterations associated with an early deposition of fat, not easily detectable by organotropic dye techniques.