Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1992
Sevoflurane is biotransformed by guinea pig liver slices but causes minimal cytotoxicity.
Guinea pig liver slices were used to evaluate the biotransformation and hepatotoxic potential of sevoflurane. Precision-cut liver slices (250-300 microns thick) were incubated in sealed roller vials in buffer at 37 degrees C under 95% O2. Sevoflurane was added to produce 0.9 or 2.1 mM medium concentrations. ⋯ Sevoflurane (2.1 mM) and isoflurane (2.3 mM) had no effect on slice K+ content, but both anesthetics depressed protein synthesis. The biotransformation of sevoflurane was maximal at 95% O2, with threefold more F- produced from sevoflurane than isoflurane. Sevoflurane appears to have a minimal effect on the guinea pig liver slices, which is consistent with in vivo studies in which minimal or no hepatotoxicity has been observed.
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Anesthesia and analgesia · Sep 1992
Comparative StudyBlood flow and tissue oxygen pressures of liver and pancreas in rats: effects of volatile anesthetics and of hemorrhage.
The object of this investigation was to compare the effects of volatile anesthetics and of hemorrhage at comparable arterial blood pressures on splanchnic blood flow (radioactive microspheres) and tissue oxygenation of the liver and pancreas (surface PO2 [PSO2] electrodes). In contrast to earlier studies, we did not use identical minimum alveolar anesthetic concentration multiples as a reference to compare volatile anesthetics; rather, we used the splanchnic perfusion pressure. Under general anesthesia (intravenous chloralose) and controlled ventilation, 12 Sprague-Dawley rats underwent laparotomy to allow access to abdominal organs. ⋯ Thus, volatile anesthetics preserved pancreatic but not hepatic blood flow and tissue oxygenation in this rat model. Despite comparable effects on perfusion, the PSO2 of the liver and pancreas was the least during hemorrhagic hypotension compared to that with the anesthetics. Because the volative anesthetic-induced hypotension has such a different effect on splanchnic tissue oxygenation compared with hemorrhagic-induced hypotension, the authors conclude that the method of inducing hypotension may have different effects on oxygenation of various tissues.
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Anesthesia and analgesia · Sep 1992
Neuromuscular pharmacology in rat neonates: development of responsiveness to prototypic blocking and reversal drugs.
The neonatal pharmacology of neuromuscular drugs was studied in vivo in newborn rats and in vitro in neonatal phrenic nerve-hemidiaphragm preparations. Drugs used to probe neuromuscular development in rat neonates were physostigmine, edrophonium, neostigmine, 4-aminopyridine, d-tubocurarine (dTc), and succinylcholine. The prejunctional actions of these drugs were monitored in relation to neonatal age by the appearance of stimulus-evoked repetitive discharge initiated by motor nerve endings and the occurrence and magnitude of the resulting enhancement of twitch tension. ⋯ Rat neonates showed resistance to dTc blockade when tested by neonatal phrenic nerve-hemidiaphragm preparations in vitro. Relationships between age and 85%-95% transmission block declined to the adult level by week 5. This result indicates that in rat neonates, pharmacodynamic rather than pharmacokinetic mechanisms predominate in the development of responsiveness to dTc.
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Anesthesia and analgesia · Sep 1992
Comment Letter Biography Historical ArticleRalph Waters' ghost and the AUA.