Figure 3.

Propionylcholine (500 μM at the serosal side, upper row) or butyrylcholine (500 μM at the serosal side, lower row) were repeatedly administered to mucosal–submucosal (left column) or mucosal (right column) preparations of rat distal colon. The serosal compartment was washed three times with five times the chamber volume before the next administration of the respective choline ester. Values are given as means (black symbols) ± SEM (grey area), n = 6 for propionylcholine and n = 8 for butyrylcholine. Line interruptions are caused by omission of time intervals in order to synchronize the tracings of individual records to the administration of the respective agonists.