ISSN:
1432-136X
Keywords:
Key words Superoxide enzyme inactivation
;
Oxidative stress
;
Ileum smooth muscle
;
Limulus polyphemus
;
Argopecten irradians
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract Mammalian lactate dehydrogenase and phosphofructokinase are more susceptible in vitro to superoxide (O&/dot; 2) and hydroxyl (⋅ OH) radicals than pyruvate kinase and glucose-6-phosphate dehydrogenase, suggesting that differential inactivation of regulatory enzymes contributes to the metabolic disintegration in stenoxic tissues during transient hypoxia. Likewise, creatine kinase in smooth muscle from porcine ileum is significantly reduced by hypoxia-reoxygenation ex vivo from 300 (±18.2 SE, n=8) to 196 U ⋅ g wet wt-1 (±16.7, P〈0.001, ANOVA). Conversely, arginine kinase, from the myocardium of Limulus polyphemus, a species that tolerates anoxia for days was 2.9-fold less susceptible to oxidative inactivation. To examine whether preservation of kinase function is related to euryoxic capacity, a combination of non-invasive 31P-NMR spectroscopy and enzyme-linked assays was used to follow ATP and phosphagen status during hypoxia-reoxygenation in porcine ileum smooth muscle, L. polyphemus myocardium, and the myocardium of Argopecten irradians, a scallop species tolerant of hypoxia for only 24 h. Despite wide differences in phylogeny, euryoxic capacity and oxidative vulnerability of the phosphagen kinases, in all three tissues, the phosphagen pool recovered concomitant with ATP during reoxygenation, thereby revealing competent kinase function. In the mammalian tissue, such preservation of kinase function is facilitated by a 2400-fold excess of enzyme activity.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s003600050020
Permalink
