i Poiutzc& F.: Pharmacological characterization of neural mechanisms regulating mucosal ion transport in mouse jejunum

Neural regulation of electrolyte transport in mouse jejunum was investigated in vitro using: 1) a full-thickness intestinal segment (intact preparation) and 2) a mucosal preparation, consisting of only mucosa, basement membrane and muscularis mucosa. In Ussing chambers, intact tissues exhibited high- and low-fre-quency oscillations of basal transmural potential difference (PD) and short-circuit current (L) whereas mucosal tissues exhibited only low-frequency oscillation of these parameters. High-fre-quency oscillations of PD and l were found to originate from muscle activity. Under basal conditions, intact tissues exhibited net Na absorption and net CI secretion, whereas mucosal tissues displayed greater net Na absorption and net Cl ab-sorption. When applied to the serosal medium of intact tissues, tetrodotoxin, a neurotoxin, and chiorisondamine, a ganglionic blocking agent, caused a concentration-dependent reduction o