[Histochemical quantification of muscular ischemia: effect of treatment with naftidrofuryl]

Evaluation of degree of muscle ischemia of a limb and its reversibility is a poorly resolved practical problem, and it has not been clarified whether vasodilatory and circulatory spasmolytic substances possess, in addition to an effect of increasing irrigation, any direct action on muscle cell energy metabolism. An experimental study used histochemical techniques to evaluate oxidative enzyme activity of tissues. The compound tetrazolium nitro-blue (NBT), when reduced by tissue dehydrogenases, has the property of producing a dense non-crystalline blue pigment designated "formazan". During muscle ischemia, the time of appearance of this reaction increases with degree of ischemia through the bias of the decrease or disappearance of succinate-dehydrogenases. Transient ischemia of hindpaw, over 3, 6, 9, 12, 15 and 18 hours, was provoked by tourniquet in 49 rats treated with a vasodilator (naftidrofuryl) and 21 untreated (control) rats. Spontaneous revascularization occurred after removal of the tourniquet. Muscles were studied by microsurgical removal of specimens on removal of tourniquet and 1 and 12 hours and 3, 7 and 14 days after its removal (fig. 1 and 2). Times for staining of muscles with tetrazolium were measured and curves of comparative times established (fig. 3 and 4). Histopathologic specimens were also obtained at the same periods (fig. 5, 6, 7). Results of histochemical studies with tetrazolium and with quantitative determination of degree of cellular anoxia showed the action of naftidrofuryl to be related to mitochondrial metabolism of skeletal muscle, specifically for succinate-dehydrogenase. Clinical application in the determination of therapy and of functional prognosis of an ischemic limb is a possibility by the use of the NBT test in vascular surgery.