title: Semipermeable membranes for improving the histochemical demonstration of enzyme activities in tissue sections. V. Isocitrate: NADP+ oxidoreductase (decarboxylating) and malate: NADP+ oxidoreductase (decarboxylating).
abstract: Improved histochemical techniques for the demonstration of NADP+-specific isocitrate dehydrogenase and malate dehydrogenase in tissue sections are described. With these techniques a semipermeable membrane is interposed between the incubating solutions and the tissue sections preventing diffusion of enzymes into the medium during incubation. In the histochemical system the NADP+-dependent enzymes catalyze the electron transfer from threo-Ds-isocitrate or L-malate into NADP+. Phenazine methosulphate and menadione serve as intermediate electron acceptors between reduced coenzyme and nitro-BT. Sodium-azide and amytal are incorporated into the incubating-medium to block electron transfer to the cytochromes. For demonstrating enzyme activities in sections containing non-specific alkaline phosphatase, a phosphatase inhibitor is added into the incubation media. Problems involved in the histochemical demonstration of both enzymes are discussed.
mesh_terms: D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors; D000818:Animals; D002482:Cellulose; D004579:Electron Transport; D005629:Frozen Sections; D006651:Histocytochemistry / Q000379:methods*; D006652:Histological Techniques; D006801:Humans; D007521:Isocitrate Dehydrogenase / Q000032:analysis*; D008291:Malate Dehydrogenase / Q000032:analysis*; D008567:Membranes, Artificial; D008773:Methylphenazonium Methosulfate; D051379:Mice; D009249:NADP / Q000378:metabolism; D009580:Nitroblue Tetrazolium; D010070:Oxalates; D011817:Rabbits; D051381:Rats; D014812:Vitamin K
chemical_list: D008567:Membranes, Artificial; D010070:Oxalates; D014812:Vitamin K; D009580:Nitroblue Tetrazolium; D008773:Methylphenazonium Methosulfate; D009249:NADP; D002482:Cellulose; D008291:Malate Dehydrogenase; D007521:Isocitrate Dehydrogenase; D000469:Alkaline Phosphatase