Naturally occurring variability in anesthetic potency among inbred mouse strains

We measured the naturally occurring variability in anesthetic potency, defi ned by the minimum alveolar anesthetic concentrations (MACs) of inhaled ane sthetics required to produce immobility in response to noxious stimuli, in seven widely used laboratory mouse strains. To these data, we added similar data for eight other mouse strains. The average MAC values for each anesth etic for the 15 strains were normally distributed, with a coefficient of va riation (ratio of so to mean) of 0.1. The range of MAC values was 39% for d esflurane, 44% for isoflurane, and 55% for halothane. MAC values were highl y reliable, with approximately 1% of the variance in MAC measurements for t he strains being explained by measurement error. One hundred forty-six stat istically significant differences among the 15 strains were found for the t hree inhaled anesthetics (isoflurane, desflurane, and halothane). Our resul ts suggest that multiple genes underlie the observed variability in anesthe tic potency.