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Query: UMLS:C0242706 (hyperoxia)
 5,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To study the ultrastructural effects of hyperoxia on the kidney, young adult Sprague Dawley rats were exposed to 3 atmospheres absolute (ATAs) of pure oxygen for 5 hours and were killed in a time sequence varying from immediately to 30 days after exposure. Their renal cortices were processed for electron microscopy. Selective mitochondrial changes were observed within sublethally and transiently altered proximal tubular epithelial cells. The most consistent finding was the accumulation of 0.08 mu to 0.5 mu round to ovoid homogeneous matrical inclusions which frequently formed larger confluent amorphous masses. The inclusions stained intensely with lead and uranium but appeared homogeneously electron-lucent in unstained sections. Energy-dispersive x-ray analysis revealed that they did not contain calcium or phosphorus. The inclusions were different from the innately electron-opaque flocculent densities commonly found in pathologically altered mitochondria. Since the mitochondria containing them were removed by autophagocytosis, it is suggested that the inclusions were associated with selective mitochondrial degeneration induced by hyperoxia. No glomerular lesions were found.
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PMID:Selective mitochondrial degeneration in renal tubules following hyperbaric oxygen exposure. 22 8

Mitochondrial energy coupling in the gerbil brain was characterized by the relationship between intracellular phosphocreatine (PCr)/inorganic phosphate (Pi), phosphorylation ratio, and the mitochondrial redox state in graded hypoxia. Phosphorus-nuclear magnetic resonance (NMR) spectra of the brain and whole head were taken by surface and saddle coil, respectively. The NADH level of the brain cortex was monitored by in vivo fluororeflectometry. The PCr and Pi of the head and brain did not change between 100 and 10% O2 inhalation. PCr progressively decreased and Pi progressively increased with 6 and 4% 0% inhalation in the head. The PCr/Pi of the brain decreased by 44% at 6% fraction of inhaled oxygen (FIO2) and 57% at 4% FIO2. The ATP level did not change during hypoxia. The calculated phosphorylation ratio of the brain ([PCr] Kck[H+]/[Cr][Pi]) = ([ATP]/[ADP][Pi]) was 4.1 X 10(4) M-1 in normoxia. Hypoxia of increasing severity induced increasing NAD reduction of the brain cortex with 17% NAD reduction at 10% FIO2 when there was no change in phosphorylation ratio. The phosphorylation ratio decreased, i.e., the mitochondria failed to maintain the energy level of the brain when the magnitude of the change in NAD reduction to hypoxia was half of the total redox change between hyperoxia and anoxia. These studies demonstrated the feasibility of combined 31P-NMR and NADH fluorometry measurements on brain in vivo. The observations show similarities between the responses of mitochondrial oxidative phosphorylation to hypoxia in vivo and in vitro.
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PMID:Correlated in vivo 31P-NMR and NADH fluorometric studies on gerbil brain in graded hypoxia and hyperoxia. 336 55

In vivo 31P-magnetic resonance spectroscopy (MRS) with a chronically implanted detection coil was used to study the effect of hypoxia on the phosphorus metabolites and intracellular pH in the liver of infant rabbits. A two-turn 10-mm radiofrequency coil was placed between the hepatic lobes in each of four infant New Zealand white rabbits (10-16 days old). Two days later, the rabbits were anesthetized and mechanically ventilated with 1.5% isoflurane in 98.5% O2. Blood gases, heart rate, and mean arterial pressure were monitored. 31P-MR spectra were continuously obtained every 5 minutes during 15 minutes of hyperoxia (PaO2 greater than 250 torr), 15 minutes normoxia (PaO2 approximately equal to 100 torr), 60 minutes hypoxia (PaO2 = 24 torr +/- 4 S.D.), and 15 minutes recovery (hyperoxia). In addition, 31P-MR spectra of perchloric-acid extracts of the liver of an adult and of an infant rabbit, removed under normoxic conditions, were examined. The 31P-MR spectra of liver of the normoxic adult (in vitro) and infant rabbits (in vitro and in vivo) revealed a high level of phosphodiesters, namely glycerol-3-phosphorylethanolamine, glycerol-3-phosphorylcholine, and phosphoenolpyruvate, compared with that reported for adult rat and adult mouse liver. The inorganic phosphate (Pi)-to-adenosine triphosphate (ATP) ratio was about 0.90 during hyperoxia and during normoxia. Within 15 minutes after induction of hypoxia, the level of phosphorus metabolites changed markedly: The ATP decreased 41% +/- 18 S.D. (P less than .01) and the Pi increased 206% +/- 29 S.D. (P less than .01); the Pi/ATP ratio was 5.0.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:In vivo 31P-MR spectroscopy of the liver in the infant rabbit to study the effect of hypoxia on the phosphorus metabolites and intracellular pH. 395 89