In vitro effects of bethanechol on abomasal and duodenal smooth muscle preparations from dairy cows with left displacement of the abomasum and from healthy dairy cows.

This study investigated the effects of bethanechol (BeCh) on abomasal and duodenal smooth muscle preparations from dairy cows with left displacement of the abomasum (LDA) and from healthy dairy cows, and determined the role of muscarinic acetylcholine receptor subtypes 2 and 3 (M(2) and M(3)) in mediating contraction. Concentration-response curves for BeCh, with or without prior incubation with an M(2) antagonist (AF-DX 116) or an M(3) antagonist (4-DAMP), were established and evaluated. BeCh induced a significant, concentration-dependant increase in the contractility variables for all locations in both groups of cows.