Articles: anesthetics.
-
The effect of increasing the concentration of sevoflurane anaesthesia on diaphragmatic function was investigated in six mechanically ventilated dogs. Diaphragmatic function was assessed by measuring the transdiaphragmatic pressure (Pdi) generated during bilateral supramaximal stimulation of the cervical phrenic nerves at frequencies of 0.5, 10, 20, 50, and 100 Hz under quasi-isometric conditions. Measurements were performed at 1, 1.5 and 2 MAC concentrations after maintaining stable conditions for one hour. ⋯ In addition, no change in Pdi during 10, 20, 50 Hz stimulation was noted at any of the three levels of anaesthesia. By contrast, Pdi with 100 Hz stimulation during 2 MAC sevoflurane exposure (28.1 +/- 5.0 cmH2O) decreased below Pdi levels seen at 1 and 1.5 MAC (35.3 +/- 4.3 cmH2O and 31.5 +/- 4.3 cmH2O, respectively) (P less than 0.05). From these results, we conclude that sevoflurane impairs diaphragmatic function in deep anaesthesia.
-
Ann. N. Y. Acad. Sci. · Jan 1991
ReviewRole of signal transduction in anesthetic action. Alpha 2 adrenergic agonists.
The molecular mechanism for general anesthetic action is not known. The alpha 2 adrenergic agonists represent a novel class of "anesthetic-like" agent because of their selectivity for receptor binding sites and because the transmembrane signaling systems mediating their biologic responses in non-CNS systems are known. We have begun to characterize the signal transduction pathway involved in the anesthetic-like action of the alpha 2 adrenergic agonists. ⋯ Subsequently, data using molecular biologic techniques suggested that the alpha 2 C4 isoreceptor was the probable receptor that mediated the anesthetic response. We further explored the postreceptor effector mechanism for the signal transduction pathway for alpha 2 anesthetic action and identified the participation of two other molecular components, namely, a pertussis-toxin-sensitive G protein and a 4-aminopyridine-sensitive ion channel. Whether the signal transduction pathway for alpha 2 anesthetic action mediates the further response to other non-alpha 2 anesthetic agents needs to be defined.
-
Ann. N. Y. Acad. Sci. · Jan 1991
ReviewSaturable binding of anesthetics to nicotinic acetylcholine receptors. A possible mechanism of anesthetic action.
Recent controversies in the existence of saturable binding of general anesthetics in brain tissues prompted a careful examination of specific binding of anesthetics to neural receptors. We examined the binding of both local and general anesthetics using electron spin resonance and radioligand criteria. ⋯ Association of anesthetic at this crevice is in turn dependent on the anesthetic concentration in the lipid phase of the membrane. The hypothesis provides a mechanism for the saturable interaction of anesthetics with their protein target site in the membrane without violating the correlations expressed by the Meyer-Overton rule of anesthetic action.