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Assessing Changes in Volatile General Anesthetic Sensitivity of Mice after Local or Systemic Pharmacological Intervention
Published on: October 16, 2013
Strain differences in murine ventilatory behavior persist after urethane anesthesia
Iahn Gonsenhauser1, Christopher G Wilson, Fang Han
1Division of Pulmonary and Critical Care Medicine, Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4941, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|August 31, 2004
Summary
Genetic differences in mouse respiratory patterns persist even under anesthesia. A/J mice consistently exhibit slower, deeper, and more variable breathing than B6 mice, indicating robust genetic control of breathing. The neural basis for these traits is partly subcortical.
Area of Science:
- Neuroscience
- Respiratory Physiology
- Genetics
Background:
- Significant differences exist in breathing patterns between awake C57BL/6J (B6) and A/J mouse strains.
- A/J mice display slower, deeper, and more variable breathing compared to B6 mice.
- Urethane anesthesia's impact on cortical and subcortical function was investigated to test if a fully functional neuroaxis is required for these strain differences.
Purpose of the Study:
- To investigate the hypothesis that strain-specific breathing differences in mice require a fully functional neuroaxis.
- To determine if urethane anesthesia alters or maintains the distinct respiratory patterns observed between B6 and A/J mouse strains.
Main Methods:
- B6 and A/J mice were anesthetized with urethane and placed in a whole-body plethysmograph.
- Respiratory frequency (Fr), inspiration/expiration durations, and amplitude were measured under normoxia, hyperoxia, hypoxia, and post-hypoxia.
- Breathing variability was quantified using the coefficient of variation (CV) and spatial statistics on Poincaré plots.
Main Results:
- Anesthetized A/J mice maintained slower, deeper, and more variable breathing than B6 mice at rest and during hyperoxia.
- During hypoxia, respiratory frequency and its variability were not significantly different between strains.
- Post-hypoxia, B6 mice showed reduced Fr and increased variability compared to baseline, unlike A/J mice, with strain differences confirmed by spatial analysis.
Conclusions:
- Strain-specific differences in respiratory pattern and variability are robust genetic traits in mice.
- These distinct respiratory characteristics are maintained under urethane anesthesia.
- The neural substrates underlying these differences are, at least partially, located within subcortical structures.
