High throughput modular chambers for rapid evaluation of anesthetic sensitivity

Abstract

BackgroundAnesthetic sensitivity is determined by the interaction of multiple genes. Hence, a dissection of genetic contributors would be aided by precise and high throughput behavioral screens. Traditionally, anesthetic phenotyping has addressed only induction of anesthesia, evaluated with dose-response curves, while ignoring potentially important data on emergence from anesthesia.MethodsWe designed and built a controlled environment apparatus to permit rapid phenotyping of twenty-four mice simultaneously. We used the loss of righting reflex to indicate anesthetic-induced unconsciousness. After fitting the data to a sigmoidal dose-response curve with variable slope, we calculated the MACLORR (EC50), the Hill coefficient, and the 95% confidence intervals bracketing these values. Upon termination of the anesthetic, Emergence timeRR was determined and expressed as the mean ± standard error for each inhaled anesthetic.ResultsIn agreement with several previously published reports we find that the MACLORR of halothane, isoflurane, and sevoflurane in 8–12 week old C57BL/6J mice is 0.79% (95% confidence interval = 0.78 – 0.79%), 0.91% (95% confidence interval = 0.90 – 0.93%), and 1.96% (95% confidence interval = 1.94 – 1.97%), respectively. Hill coefficients for halothane, isoflurane, and sevoflurane are 24.7 (95% confidence interval = 19.8 – 29.7%), 19.2 (95% confidence interval = 14.0 – 24.3%), and 33.1 (95% confidence interval = 27.3 – 38.8%), respectively. After roughly 2.5 MACLORR • hr exposures, mice take 16.00 ± 1.07, 6.19 ± 0.32, and 2.15 ± 0.12 minutes to emerge from halothane, isoflurane, and sevoflurane, respectively.ConclusionThis system enabled assessment of inhaled anesthetic responsiveness with a higher precision than that previously reported. It is broadly adaptable for delivering an inhaled therapeutic (or toxin) to a population while monitoring its vital signs, motor reflexes, and providing precise control over environmental conditions. This system is also amenable to full automation. Data presented in this manuscript prove the utility of the controlled environment chambers and should allow for subsequent phenotyping of mice with targeted mutations that are expected to alter sensitivity to induction or emergence from anesthesia.

Is Hydrogen Sulfide-Induced Suspended Animation General Anesthesia?

“…When combined with isoflurane, however, the EC 50 concentration of isoflurane is significantly decreased. This is consistent with prior work where suppression of respiratory complex I activity via mutation dramatically increased the anesthetic sensitivity in both animals and humans (Morgan et al, 2002;Kayser et al, 2004;Sun et al, 2006;Volpato et al, 2008). However, as mentioned above, the antagonism between H 2 S and isoflurane on CO 2 production make it unlikely that LORR synergy is produced via mitochondrial pathways.…”

“…Chamber and gas flow setup has been reported previously (Sun et al, 2006). Temperature was maintained by using a heated water bath to maintain euthermia.…”

The Effects of Anesthetic Agent and Carrier Gas on Blood Glucose and Tissue Uptake in Mice Undergoing Dynamic FDG-PET Imaging: Sevoflurane and Isoflurane Compared in Air and in Oxygen

“…Animals were anesthetized singly in a prewarmed induction box prior to being promptly transferred to the bed of the PET scanner. Light anesthesia was maintained for restraint only at the minimum concentration required to ensure the mice did not wake up during the scan, about 2% v/v for isoflurane (Baxter Healthcare, Deerfield, IL, USA) or about 3.5% v/v for sevoflurane (Abbott Labs, North Chicago, IL, USA) consistent with previous reports [12].. The eyes were lubricated with ophthalmic ointment.…”

An essential role for orexins in emergence from general anesthesia

“…Induction and emergence from isoflurane or sevoflurane were defined behaviorally as the respective loss and return of the righting reflex and were evaluated as follows. Mice were placed in cylindrical gas-tight, controlled-environment chambers arrayed in parallel (35). After 90 min of habituation with 100% oxygen each day on two successive days, anesthesia was induced with a Drä ger model 19.1 isoflurane or sevoflurane vaporizer by using 8 -12 stepwise incremental increases in the concentration of anesthetic gas dissolved in 100% oxygen.…”

“…After 90 min of habituation with 100% oxygen each day on two successive days, anesthesia was induced with a Drä ger model 19.1 isoflurane or sevoflurane vaporizer by using 8 -12 stepwise incremental increases in the concentration of anesthetic gas dissolved in 100% oxygen. Anesthetic gas concentrations were determined in triplicate during the last 2 min at each step (35). Initial volatile anesthetic concentrations were 0.44% isoflurane or 0.96% sevoflurane.…”