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Effect of graded hypoxia on the rat hepatic tissue oxygenation and energy metabolism monitored by near‐infrared and 31 P nuclear magnetic resonance spectroscopy
Author(s) -
Seifalian Alexander M.,
El-Desoky El-Hamid,
Delpy David T.,
Davidson Brian R.
Publication year - 2001
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.01-0308com
Subject(s) - hypoxia (environmental) , chemistry , nucleoside triphosphate , oxygen , oxygenation , adenosine triphosphate , metabolism , intracellular , nuclear magnetic resonance spectroscopy , hepatocyte , intracellular ph , cytochrome c oxidase , biochemistry , medicine , nucleotide , enzyme , in vitro , stereochemistry , organic chemistry , gene
Alteration in hepatic cellular adenosine triphosphate (ATP) levels has been shown to be a sensitive index for hypoxic damage. Hepatic ATP metabolism can be monitored by 31 P nuclear magnetic resonance (NMR). Near‐infrared spectroscopy (NIRS) can measure tissue oxyhemoglobin (HbO 2 ), deoxyhemoglobin (Hb), and cy‐;tochrome oxidase (Cyt Ox), which reflect ATP production. In this study, hepatic oxygenation parameters have been correlated with ATP metabolism under graded hyp‐;oxia. Sprague‐;Dawley rats underwent laparotomy for liver exposure. NIRS probes and an NMR coil were placed on the liver and the animal was positioned in the NMR magnet. Graded hypoxia was achieved by a stepwise reduction of the fraction of inspired oxygen (FiO 2 ) from 15 to 4%. Recovery between the hypoxic periods was achieved using 30% oxygen. Hepatic tissue oxygenation parameters were measured continuously by NIRS; 31 P‐;NMR spectra obtained at 1 min intervals from energy metabolites and intracellular pH were calculated. All the hypoxic grades produced an immediate reduction in HbO 2 with a simultaneous increase in Hb. Cyt Ox was reduced significantly only with FiO 2 of ≤ 10%. 31 P‐;NMR spectra showed a significant decrease in cellular β nucleoside triphosphate (β‐;NTP) only with FiO 2 of ≤ 10%. Significant correlation was seen between β‐;NTP and HbO 2 ( r =0.85), Hb (r=‐;0.74), and Cyt Ox ( r =0.81). Cyt Ox was reduced with intracellular hypoxia and correlated temporally with the reduction of cellular β‐;NTP, and therefore could be used as an index for the changes in β‐;NTP with hypoxia.—Seifalian, A. M., El‐Desoky, E.‐H., Delpy, D. T., Davidson, B. R. Effect of graded hypoxia on the rat hepatic tissue oxygenation and energy metabolism monitored by near‐infrared and 31 P nuclear magnetic resonance spectroscopy. FASEB J. 15, 2642–2648 (2001)