Cholinesterase activity in pig airways and epithelial cells.

Acetylcholinesterase (AChE, EC 3.1.1.7) and butyrylcholinesterase (BChE, EC 3.1.1.8) activities were detected in bronchial and bronchial epithelial cell homogenates of the pig. In the bronchial homogenates, the maximal upstroke velocity (Vmax) of AChE and the maximal velocity after second substrate fixation (Vss) of BChE were 5.70 +/- 0.46 and 7.87 +/- 0.81 mU/mg protein, respectively. In the epithelial cell homogenates, a smaller amount of cholinesterase (ChE) was found: Vmax was 0.62 +/- 0.29 and Vss was 1.56 +/- 0.33 mU/mg protein for AChE and BChE, respectively. AChE activity was increased by 21 +/- 5% in the bronchial homogenates and by 54 +/- 14% in the epithelial cell homogenates, when intact bronchial segments were incubated with a cyclooxygenase inhibitor, indomethacin (INDO). These results suggest that prostanoids may be involved in the regulation of AChE activity in pig airways.