The volatile anesthetic halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) is extensively metabolized in humans, with approximately 50% of an absorbed dose undergoing hepatic biotransformation (Carpenter et al., 1986). Halothane is a unique substrate, undergoing both oxidative and reductive P450-catalyzed dehalogenation during clinical anesthesia, with each metabolic pathway subtending a differ...

The volatile anesthetic halothane undergoes substantial biotransformation generating metabolites that mediate hepatotoxicity. Aerobically, halothane undergoes cytochrome P450-catalyzed oxidation to trifluoroacetic acid (TFA), bromide and a reactive intermediate that can acetylate liver proteins. These protein neo-antigens stimulate an immune reaction that mediates severe hepatic necrosis ("halo...

Changes in ventilatory variables (VE, VE, f, Tl/Ttot, VT/Tl, PE'CO2) were studied in 12 unpremedicated children, weighing between 10 and 20 kg, during halothane anaesthesia. At an inspired concentration of 0.5% halothane, respiratory rate increased, VT decreased, and VE did not change markedly. When the inspired halothane concentration increased further, there was a significant decrease in VE, ...

Induction and recovery characteristics of isoflurane anaesthesia were compared with halothane anaesthesia during outpatient myringotomy and placement of Sheely ventilation tubes in 101 unpremedicated children. Compared with halothane, isoflurane resulted in prolonged induction times and inferior induction scores due to increased salivation, coughing, breathholding and laryngospasm. However, whe...

PURPOSE To examine the effect of halothane on the cytosolic Ca2+ concentration ([Ca2+]i)-tension relationship of rat aortic smooth muscle. METHODS Rat aortic rings without endothelia were loaded with the fluorescent Ca2+ indicator, Fura PE3-AM, and then mounted in organ baths. The changes in isometric tension and [Ca2+]i were measured simultaneously. In one series ionomycin (10 nM-3 microM) w...

The goal of this study was to develop a human physiologically based pharmacokinetic (PBPK) model for the chemical HCFC-123 (2,2-dichloro-1,1,1-trifluoroethane) and its major metabolite, trifluoroacetic acid (TFA). No human kinetic data for HCFC-123 are available, thus a corollary approach was developed. HCFC-123 is a structural analog of the common anesthetic agent halothane (2-bromo-2-chloro-1...

The effect of halothane and nitrous oxide on the capacity of natural killer (NK) lymphocytes from female patients with benign and malignant breast disease to kill the tumour cell line K562, was studied in vitro. There was no depression of activity of NK lymphocytes when exposed to 2% halothane and 66% nitrous oxide either alone or in combination. However, NK lymphocyte activity was depressed at...

The hemodynamic consequences and myocardial blood flow alterations associated with cross-clamping of the thoracic aorta were studied during pentobarbital (control), halothane (1 MAC), and isoflurane (1 MAC) anesthesia in dogs with a critical stenosis of the left circumflex coronary artery. Aortic clamping at the level of the diaphragm resulted in significant and equivalent increases in mean aor...

BACKGROUND The activity of canine expiratory (E) neurons in the caudal ventral respiratory group is primarily dependent on N-methyl-D-aspartic acid (NMDA) receptor-mediated excitatory chemodrive inputs and modulated by an inhibitory mechanism mediated via gamma-aminobutyric acidA (GABA(A)) receptors. In an intact canine preparation, halothane depressed the activity of these neurons mainly by re...

The action of halothane on sinoatrial, ventricular, and Purkinje fibers was studied by means of intracellular microelectrodes. Rabbit atrial fibers were not very sensitive to even high (2%) concentrations of halothane. Sheep Purkinje fibers showed a significant hyperpolarization from 82 mv to 87 mv, a marked shortening of the duration of the action potential from 370 msec to 233 msec, and a dim...