Acetylcholine Exerts Inhibitory and Excitatory Actions on Mouse Ileal Pacemaker Activity: The Role of Muscarinic versus Nicotinic Receptors.

Acetylcholine Exerts Inhibitory and Excitatory Actions on Mouse Ileal Pacemaker Activity: The Role of Muscarinic versus Nicotinic Receptors. Am J Physiol Gastrointest Liver Physiol. 2020 Jun 01;: Authors: Liu JYH, Du P, Rudd JA Abstract The effect of acetylcholine (ACh) on pacemaking and spontaneous contractions in the gastrointestinal tract is not well-characterized. The current study aims to profile the effect of several muscarinic and nicotinic receptor agonists and antagonists on pacemaker potentials in the ICR mouse ileum. Pacemaker potentials of whole-thickness mouse ileal segments were recorded extracellularly using a 60-channel microelectrode array (MEA) platform. A spatiotemporal analysis integrated the frequency, amplitude and velocity measurements of pacemaker currents. Comparative data were obtained by recording spontaneous smooth muscle tone in a conventional organ bath. On the MEA, ACh (0.3-300 μM) and bethanechol (0.3-300 μM) reduced ileal pacemaker potentials, significantly. The inhibitory effect of ACh was mimicked by donepezil (300 μM), but not nicotine (0.3-7 mM). Atropine (300 μM), but not hexamethonium (300 μM), reversed the inhibitory actions of ACh and bethanechol and revealed excitatory properties manifested as increases in pacemaker frequency. A spatial analysis also revealed that atropine, but not hexamethonium, reversed the ACh-induced distortion of pacemaker propagation activity. Atropine (0.001-3 mM)...
Source: American Journal of Physiology. Gastrointestinal and Liver Physiology - Category: Physiology Authors: Tags: Am J Physiol Gastrointest Liver Physiol Source Type: research