Journal of anesthesia
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Journal of anesthesia · Sep 1995
Dose-dependent effects of repeated ketamine administration on muscarinic acetylcholine receptors in the mouse forebrain.
To study the effects of repeated ketamine administration (0: saline, 12.5, 25, and 50 mg·kg-1 every 3 days for a total of five times, subcutaneously) on the central muscarinic acetylcholine receptors (mAchRs), receptor binding assays of mAchR were carried out in the forebrain of mice, using [3H]quinuclidinyl benzilate ([3H]QNB) as a ligand. We also examined whether repeated ketamine administration could modify the sensitivity to scopolamine (0.5 mg·kg-1) (a muscarinic antagonist). ⋯ Repeated ketamine reduced scopolamine-induced hyperlocomotion at 50 mg·kg-1 (P<0.05). We conclude that repeated ketamine administration produces up-regulation of mAchRs, which is probably associated with the altered Ach transmission of the central nervous system.
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Journal of anesthesia · Sep 1995
The effects of isoflurane and sevoflurane on the left ventricular end-systolic pressure-volume relation in dogs.
The influence of two inhalational anesthetics, isoflurane and sevoflurane, on the end-systolic pressure-volume relations (ESPVR) of the left ventricle (LV) in situ was investigated in open-chest dogs anesthetized with α-chloralose. The LV volume was measured by a conductance catheter while the LV pressure was measured by a tipmicromanometer. The end-systolic elastance (Ees) of the LV was calculated as the slope of ESPVR which was elicited when the inferior vena cava was transiently occluded. ⋯ Isoflurane and sevoflurane caused equivalent decreases in Ees of 23% and 16% at 1 MAC, and 48% and 41% at 2 MAC, respectively. Dobutamine 3 μg·kg-1·min-1 produced a simultaneous restoration of Ees and recovery of the cardiac output at 1 and 2 MAC of both isoflurane and sevoflurane. We thus conclude that the depressant effect of sevoflurane on cardiac contractility is almost identical to that of isoflurane in the dog, and they are both reversed by the use of a low dose of dobutamine.
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Journal of anesthesia · Sep 1995
Halothane suppresses the increase in intracellular calcium concentration of isolated rat myocytes during hydrogen peroxide perfusion.
Ischemia-reperfusion injury is probably caused by the generation of oxygen free radicals. The final common pathway to cell injury may be mediated by intracellular calcium overloading induced by oxygen free radicals. Volatile anesthetics have been shown to improve myocardial function following reperfusion. ⋯ Halothane delayed the onset of the increase in [Ca2+]i induced by H2O2, whereas sevoflurane and isoflurane accelerated the onset. Furthermore, sevoflurane caused more pronounced accumulation of intracellular calcium than did halothane and isoflurane. Therefore, the reduction of excessive intracellular calcium accumulation caused by halothane may have beneficial effects on myocardial function following reperfusion.
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Journal of anesthesia · Sep 1995
Does cyclosporine affect the duration of action of vecuronium in renal transplant recipients?
The duration of action of vecuronium was tested in 41 surgical patients to evaluate whether cyclosporine modulates the action of vecuronium. The patients were divided into three groups: 12 patients with normal renal function (group A); 14 renal transplant recipients who had received cyclosporine before surgery (group B); and 15 patients with chronic renal failure undergoing surgery other than renal transplantation and who did not receive cyclosporine (group C). ⋯ There was no significant difference in the duration of action of vecuronium between the patients of groups B and C. In summary, cyclosporine did not prolong the duration of action of vecuronium in the renal transplant recipients when the same dose was administered compared with the patients with chronic renal failure who did not receive cyclosporine.
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The effects of propofol on the tone of guinea pig respiratory smooth muscle was studied both in vitro and in vivo. In vitro, the activity of propofol on tracheal smooth muscle was investigated using a force displacement transducer for isometric tension responses. Isoproterenol was used as the control. ⋯ Propofol (1-4.5 mg·kg-1, i.v.) exhibited neither relaxant nor constrictor effects. It is possible that the effects of propofol observed in vitro are due to nonspecific action, while the finding of no effect in vivo could be due to different tissue sensitivity to propofol, i.e., tracheal smooth muscle may be more responsive than bronchial smooth muscle. Propofol does not seem to have any deleterious effects on airway smooth muscle.