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)

Transcutaneous PO2 (tcPO2) monitoring offers a new approach to the evaluation of drug effects. We investigated the effect of theophylline on ten premature infants with apnea. Theophylline was administered as aminophylline, 8 mg/kg per rectum every 12 hours for two doses and 4 mg/kg every 12 hours for a total of two or five days (short and long courses). The tcPO2, heart rate (beat-to-beat), and thoracic impedance were continuously monitored during each of three 4-hour study periods: 12 hours before theophylline administration, 12 hours after initiation of theophylline therapy, and 24 to 48 hours after discontinuing the drug's use. Plasma levels were measured by a radioimmunoassay developed in our laboratory. Polygraphic recordings were analyzed without knowledge of treatment for frequency of apneic spells, mean duration of apneas, total duration of hypoxemia (tcPO2 less than or equal to 40 torr), total duration of hyperoxemia (tcPO2 greater than or equal to 100 torr), basal tcPO2, heart rate, and respiratory rate. In each case during theophylline use, cardiorespiratory patterns were altered, respirations were more regular, apneic spells were reduced, PO2 was stabilized with less hypoxia and hyperoxia, and bradycardic episodes were decreased. There was considerable variation in the response of the ten infants and a significant difference in the frequency of return of symptoms between those receiving short-term therapy and those receiving the longer course.
 ...
PMID:Transcutaneous oxygen monitoring in aminophylline-treated apneic infants. 72 12

Hippocampal and neocortical blood flows and tissue pO2 were investigated by mass spectrometry in unanaesthetized spontaneously breathing rats during kainic acid-induced seizures to determine whether adenosine is involved in the coupling of cerebral blood flow to metabolism during enhanced metabolic demand. The possible involvement of adenosine in the neuronal damage induced by seizures was also analyzed. The intrinsic effects of theophylline and the duration of the adenosine receptor blockade by this xanthine were first tested in 8 rats. Two groups of rats were then compared: one (n = 6) received kainic acid, and the other (n = 10) theophylline 15 min prior to kainic acid administration. An additional group of 10 rats was taken for classical histology 48 h after kainic acid treatment. Theophylline significantly reduced the hyperaemia observed during seizures, prevented any tissue hyperoxia and enhanced brain damage. This strongly suggests that adenosine is partly responsible for the increase in cerebral blood flow during kainic acid-induced seizures and has neuroprotective properties.
 ...
PMID:Theophylline reduces cerebral hyperaemia and enhances brain damage induced by seizures. 233 48

In the literature, it remains uncertain whether methylxanthines inhibit hypoxic pulmonary vasoconstriction. We examined the effects of theophylline and of S 9795, a new methylxanthine derivative, on multipoint mean pulmonary arterial pressure (Ppa)/cardiac index (Q) relationships in 31 intact dogs, ventilated alternately in hyperoxia (fraction of inspired oxygen, FIO2 0.4) and in hypoxia (FIO2 0.1). A sequence of two 5-point Ppa/Q plots at FIO2 0.4 and at FIO2 0.1, consecutively, was performed before and after i.v. administrations of theophylline 10 mg.kg-1 (n = 8) and 25 mg.kg-1 (n = 7), of S 9795 10 mg.kg-1 (n = 8) and of placebo (n = 8). The Ppa/Q plots were rectilinear in all experimental conditions. Over the entire range of Q studied, 2-5 l.min-1.m-2, hypoxia increased Ppa in all animals. Placebo had no effect on these Ppa/Q plots. Theophylline at the lowest dose (plasma levels from 8.4-13.6 micrograms.ml-1) and S 9795 (plasma levels from 3.0-11.2 micrograms.ml-1) did not affect Ppa/Q in hyperoxia or in hypoxia. Theophylline at the highest dose (plasma levels from 17.8-40.4 micrograms.ml-1) reduced hypoxic Ppa at all levels of Q and hyperoxic Ppa at the highest Q, from 3-5 l.min-1.m-2, and inhibited hypoxia-induced increases in Ppa. We conclude that pulmonary vasoconstriction may be preserved after the lowest doses of methylxanthines recommended for the treatment of increased bronchial tone.
 ...
PMID:Effects of theophylline and S 9795 on hyperoxic and hypoxic pulmonary vascular tone in intact dogs. 273 74