Effect of moxonidine on contractile activity of isolated large intestine in mice: role of alpha2-adrenoceptors and Ii-imidazoline receptors.

We studied the ability of moxonidine to interact with alpha2-adrenoceptors and Ii-imidazoline receptors in isolated mouse large intestine. Moxonidine caused contractions of longitudinal muscles in the large intestine, which depended on the dose of this preparation. Pretreatment with yohimbine (alpha2-adrenoceptor antagonist with low affinity for Ii-imidazoline receptors) and efaroxan (Ii-imidazoline receptor antagonist with low affinity for alpha2-adrenoceptors) abolished the effect of moxonidine. Antagonistic activity and relative selectivity of yohimbine and efaroxan suggest that the effects of moxonidine on mouse large intestine are realized via alpha2-adrenoceptors.