Acetoin metabolism in animal tissues

The acetoin-synthesizing activity has been studied in the skeletal muscles, brain, liver and spleen homogenates (numbered as the activity decreases). The acetoin-synthesizing activity drastically increases in case of the acetaldehyde excess and alcohol intoxication. The acetaldehyde concentrations of above 1.10(-3) M inhibit the liver pyruvate dehydrogenase activity and increase the non-oxidative transformation of pyruvate. Acetoin is rapidly metabolized in the organism eliminating from blood 10 minutes after its injection. Acetoin is an effective precursor in the biosynthesis of lipids.     

Lucigenin-enhanced chemiluminescence of animal tissues

Lucigenin-enhanced chemiluminescence (CL) makes it possible to study directly the reactions of superoxide anion radical (O ₂ ^? ) produced by mitochondria and is used for detection of the superoxide generated in enzyme and membrane systems, isolated mitochondria and cells, and whole animal organs. Lucigenin-enhanced CL is applicable to examination of human tissues; this assay requires small fragments as, for example, biopsies; however, no systematic studies with these objects have been conducted. In this work, we studied the lucigenin-enhanced CL in tissue specimens of various rat organs to determine its dependence on the degree of tissue fragmentation, storage time, and oxygen access. Addition of lucigenin to tissue fragment, slurry, or homogenate drastically increased CL; note that the whole tissue fragment displayed considerably lower (by 1–1.5 order of magnitude) CL intensity than the homogenate or slurry. The lucigenin-enhanced CL in tissue in the absence of stirring of the surrounding solution rapidly decreased, presumably because of a drop in the tissue oxygen level as a result of its consumption. The CL had two components, namely, lucigenin-enhanced CL and lucigenin-independent (intrinsic) CL. The tissue itself was the source of lucigenin-enhanced CL, and this CL was observed only in the case of sufficient oxygen access. The lucigenin-independent CL component was virtually independent of oxygen and was determined by the components released from the tissue specimen into the surrounding solution. Nitric oxide inhibited CL with increase in its concentration but had no essential effect on the rate of tissue oxygen consumption. These results suggest that lucigenin can be used as a very efficient chemiluminescent probe for superoxide radicals generated by tissue fragments.