Influence of 1-methyl-3-keto-4-phenylquinuclidinium bromide on rat tissue monoamine levels in vivo.

: The effects of 1-methyl-3-keto-4-phenylquinuclidinium bromide (MA540) on tissue monoamine levels in male rats have been compared to those of guanethidine. Neither compound influenced norepinephrine (NE) or 5-hydroxytryptamine (5-HT) levels in brain or epinephrine (E) levels in adrenal medulla. MA540 is about twice as potent as guanethidine as a heart NE depleting agent at both 8 and 24 h after drug administration. The durations of action of the compounds are similar. Unlike guanethidine, MA540 does not deplete NE in small intestine, which suggests that the drug may not elicit guanethidine-like intestinal side effects.