Noradrenaline inhibits neurogenic propulsive motor patterns but not neurogenic segmenting haustral progression in the rabbit colon.

Noradrenergic inhibition of propulsive motor patterns is mediated by the α2 -adrenoceptor to inhibit the neurogenic LDCs and the neurogenic clustering of FPCs. The neurogenic haustral boundary contractions are not affected, suggesting that α2- receptors are on selective neural circuits. The excitatory effect of noradrenaline on ripples may be due to the activation of adrenoceptors on interstitial cells of Cajal, but action on α1- receptors was excluded. No role for the β-adrenoceptor was found.