The Effects of Alpha-methyldopa, Reserpine, Guanethidine, and Iproniazid on Minimum Alveolar Anesthetic Requirement (MAC)

Abstract

The effects of prior administration of alphamethyldopa, reserpine, and guanethidine on the minimum alveolar concentration (MAC) of halohane were studied in dogs. The effect of iproniazid, a monoamine oxidase inhibitor, on cyclopropane MAC was studied in rats. Prior administration of alpha-methyldopa or reserpine, which reduce both central and peripheral norepinephrine levels, was associated with a reduction in MAC which was dose-related. Conversely, prior administration of iproniazid, which elevates central norepinephrine levels, resulted in an increase in MAC. MAC was not altered by prior administration of guanethidine, which reduces norepinephrine peripherally but not centrally. These results suggest that anesthetic requirement may be related in part to changes in norepinephrinc content in the brain.