Anesthesiology
-
Comparative Study
Bispectral index, entropy, and quantitative electroencephalogram during single-agent xenon anesthesia.
The aim was to evaluate the performance of anesthesia depth monitors, Bispectral Index (BIS) and Entropy, during single-agent xenon anesthesia in 17 healthy subjects. ⋯ Electroencephalogram-derived depth of sedation indices BIS and Entropy showed a delay to detect loss of response during induction of xenon anesthesia. Both monitors performed well in distinguishing between conscious and unconscious states during steady-state anesthesia. Xenon-induced changes in electroencephalogram closely resemble those induced by propofol.
-
Comparative Study
Photo-activated azi-etomidate, a general anesthetic photolabel, irreversibly enhances gating and desensitization of gamma-aminobutyric acid type A receptors.
The general anesthetic etomidate acts via gamma-aminobutyric acid type A (GABA(A)) receptors, enhancing activation at low GABA and prolonging deactivation. Azi-etomidate is a photo-reactive etomidate derivative with similar pharmacological actions, which has been used to identify putative binding sites. The authors examine the irreversible effects of azi-etomidate photo-modification on functional GABA(A) receptors in cell membranes. ⋯ Azi-etomidate efficiently photo-modifies etomidate sites on GABA(A) receptors in intact cells, producing persistent functional changes that mimic its reversible effects. The results demonstrate sequential modification at more than one etomidate site per receptor. The sites display reciprocal positive cooperativity. In combination with focal photo-activation, azi-etomidate may prove useful for studies of anesthetic actions in neural circuits.
-
Comparative Study
Dexmedetomidine reduces long-term potentiation in mouse hippocampus.
Dexmedetomidine (Precedex; Abbott Laboratories, Abbott Park, IL) is a selective alpha2-adrenergic agonist that also has affinity for imidazoline receptors. In clinical studies, dexmedetomidine has sedative effects and impairs memory, but the action of dexmedetomidine on synaptic plasticity in the brain has yet to be established. In the present study, the authors investigated the effects of dexmedetomidine on two forms of synaptic plasticity-long-term potentiation (LTP) and paired-pulse facilitation-in the CA1 region of mouse hippocampal slices. ⋯ Dexmedetomidine impairs LTP in area CA1 of the mouse hippocampus via imidazoline type 2 receptors and alpha2-adrenoceptors.