ISSN:
1432-2307
Keywords:
Myocardial infarction
;
Tetrazolium salts
;
NAD
;
Oxidoreductases
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Tetrazolium salts (NBT) stain normal myocardium whereas infarcts are not stained. We tried to elucidate the staining mechanism which discriminates normal from infarcted canine myocardium. The left anterior descending coronary artery (LAD) was occluded in dogs for between 4 and 32 h. The activities of four different tissue dehydrogenases were measured after 4, 8, 16, and 32 h of ischaemia. Nicotinamide adenine dinucleotides (NAD, NADH, NADPH) were determined in needle biopsies taken from the ischaemic region 1/2, 1, 11/2, 2 and 4 h after occlusion of the LAD. In another set of experiments the NBT stain was altered by the addition of NADH, NAD, NADPH, NADP, succinate, lactate and phenazine methosulfate respectively and the effect of the added substances on the previously nonstained infarcts was examined. We further compared histochemically determined infarct size to the ultrastructural extent of infarcts. Activities of the tissue dehydrogenases did not change after 4 h of ischaemia, although the NBT stain revealed a large infarction. At that time total NAD, the sum of NAD+NADH, had decreased from about 600 pmoles/mg tissue to about 200 pmoles/mg tissue and addition of the coenzymes or succinate could “repair” the biochemical lesion. After 24 h of ischaemia the activities of dehydrogenases and diaphorases were markedly decreased. Our data indicate that loss of the reduced coenzymes plays a key role in identifying myocardial infarction with tetrazolium salts. In older infarctions loss of coenzymes is joined by decreased activities of dehydrogenases and diaphorases. The principal mechanisms of staining is an enzymatic cycling.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00430828
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