Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0242706 (hyperoxia)
 5,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lungs accumulate 5-hydroxytryptamine (serotonin, 5-HT) from the perfusate by a sodium-dependent, energy-requiring, saturable process. The rate-limiting step for uptake is the transport of 5-HT and not its subsequent metabolism to 5-hydroxyindoleacetic acid. Autoradiographic studies indicate that the pulmonary endothelium is the cellular site of uptake. The effect of hyperoxia on lung clearance of 5-HT was studied with isolated perfused and ventilated lungs from rats that were previously exposed to hyperoxia. Lungs were perfused with recirculating electrolyte solution and initial [5-HT] of 0.24 microM. The calculated fractional 5-HT clearance (fracion of 5-HT removed in a single pass) ws 0.77 +/- 0.02 (mean +/- SE: n = 44) for control rats. Mean fractional clearance decreased by 20% in rats exposed to 1 atm O2 for 18 hr and 30% after 4 atmospheres absolute (ata) O2 for 1 hr (p < 0.05). The effects of O2 at 4 ata were in part reversed by exposure to air for 3.5 hr and in part prevented by injection of superoxide dismutase (60 nmole/kg body weight). This degree of O2 exposure at either 1 or 4 ata had no effect on lung content of adenine nucleotides or the distribution of 3H-5HT on autoradiography. Rats maintained for 6 weeks on a vitamin E-deficient diet showed an increased effect of hyperoxia on 5-HT clearance and did not show reversal of changes after 24 hr of air breathing. The results indicate that exposure to elevatd po2 results in reversible depression of pulmonary 5-HT clearance that is potentiated by vitamin E deficiency. This suggests alteration of pulmonary endothelial membrane transport properties due to O2 toxicity.
 ...
PMID:Environmental influences on uptake of serotonin and other amines. 740 97

Due to complex influence, such as utilization and permeability of arterial vessels to oxygen, there is a considerable difference of oxygen tension between extracellular fluid and perfusate usually used in microdialysis (30-60 Torr versus 145 Torr). Dialysate dopamine and monoamine metabolites-3,4-dihydroxyphenylacetic acid, homovanillic acid and 5-hydroxyindoleacetic acid were measured under different kinds of oxygen tension solutions (145, 72, 48 Torr). In the acute and anesthetized group, dopamine, 3,4-dihydroxyphenylacetic acid, 5-hydroxyindoleacetic acid and homovanillic acid increased 72, 93, 86 and 65%, respectively when changing the perfusate from 145 Torr to near physiological 48 Torr, while in chronic and conscious group, carried out 72 h after surgery, these compounds showed obscure increases (only homovanillic acid produced a significant change of 14%). The different effect of perfusate oxygen tension on dialysate levels of monoamines in anesthetized and conscious rats might be caused by oxidative stress triggered by hyperoxia combined with anesthesia and surgical trauma.
 ...
PMID:Hyperoxia caused by microdialysis perfusion decreased striatal monoamines: involvement of oxidative stress. 1254 45