In:
Journal of Applied Physiology, American Physiological Society, Vol. 84, No. 3 ( 1998-03-01), p. 791-797
Abstract:
Dysoxia can be defined as ATP flux decreasing in proportion to O 2 availability with preserved ATP demand. Hepatic venous β-hydroxybutyrate-to-acetoacetate ratio (β-OHB/AcAc) estimates liver mitochondrial NADH/NAD and may detect the onset of dysoxia. During partial dysoxia (as opposed to anoxia), however, flow may be adequate in some liver regions, diluting effluent from dysoxic regions, thereby rendering venous β-OHB/AcAc unreliable. To address this concern, we estimated tissue ATP while gradually reducing liver blood flow of swine to zero in a nuclear magnetic resonance spectrometer. ATP flux decreasing with O 2 availability was taken as O 2 uptake (V˙o 2 ) decreasing in proportion to O 2 delivery (Q˙o 2 ); and preserved ATP demand was taken as increasing P i /ATP.V˙o 2 , tissue P i /ATP, and venous β-OHB/AcAc were plotted againstQ˙o 2 to identify critical inflection points. Tissue dysoxia required meanQ˙o 2 for the group to be critical for bothV˙o 2 and for P i /ATP. CriticalQ˙o 2 values forV˙o 2 and P i /ATP of 4.07 ± 1.07 and 2.39 ± 1.18 (SE) ml ⋅ 100 g −1 ⋅ min −1 , respectively, were not statistically significantly different but not clearly the same, suggesting the possibility that dysoxia might have commenced after V˙o 2 began decreasing, i.e., that there could have been “O 2 conformity.” CriticalQ˙o 2 for venous β-OHB/AcAc was 2.44 ± 0.46 ml ⋅ 100 g −1 ⋅ min −1 ( P = NS), nearly the same as that for P i /ATP, supporting venous β-OHB/AcAc as a detector of dysoxia. All issues considered, tissue mitochondrial redox state seems to be an appropriate detector of dysoxia in liver.
Type of Medium:
Online Resource
ISSN:
8750-7587
,
1522-1601
DOI:
10.1152/jappl.1998.84.3.791
Language:
English
Publisher:
American Physiological Society
Publication Date:
1998
detail.hit.zdb_id:
1404365-8
SSG:
12
SSG:
31
