Purinoceptor‐mediated, Capsaicin‐resistant Excitatory Effect of Allyl Isothiocyanate on Neurons of the Guinea‐Pig Small Intestine

Allyl isothiocyanate (AITC; 200 μM) caused atropine‐ and tetrodotoxin‐sensitive longitudinal muscle contraction on the guinea‐pig small intestine. The response was not influenced by hexamethonium, a functional blockade of capsaicin‐sensitive neurons or by antagonists acting at TRPV1 or TRPA1, but was abolished by the P2 purinoceptor antagonist PPADS (50 μM). It is concluded that cholinergic motoneurons are activated by a purinergic mechanism in the course of the AITC response, independently of capsaicin‐sensitive processes or even TRPA1.