Aging: effects on minimum alveolar concentration (MAC) for halothane in Fischer-344 rats.

It is well-established that the anesthetic requirement (MAC) of volatile agents such as halothane is reduced in elderly patients. The current project was designed to determine whether a similar alteration in anesthetic requirement occurs in Fischer-344 (F-344) rats, an animal model often utilized in physiology and pharmacology to examine aging-related changes. Animals were exposed to increasing or decreasing levels of halothane. After equilibration at each concentration, the response to tail-clamping was used for MAC testing. MAC was reduced approximately 17% in aged (25 months) versus young adult (5 months) animals. From these data, it is concluded that the F-344 rat may be an adequate model for examination of age-dependent alterations in the actions of volatile anesthetics.