Abstract
The influence of the mucosa on the contractile responses to cholinergic nerve stimulation in an in vitro nerve muscle preparation of ferret trachea was studied. Repeated contractions were induced by alternating direct vagal nerve stimulation (DNS) and electrical field stimulation (EFS). With intact mucosa there was a marked successive decrease of the contractile responses. During 60 minutes the responses decreased to 46 +/- 8% of baseline (Mean +/- SEM, n = 6), compared to 86 +/- 2% in preparations, in which the mucosa was initially removed. The mucosa dependent inhibition could be partly blocked by indomethacin (10 microM). The inhibitory effect could be transferred via the bath fluid from a donor preparation with intact mucosa to a recipient preparation with removed mucosa. Fluid transferred from a donor preparation with removed mucosa or from indomethacin treated preparations did not affect the contractile responses in the recipient preparation. We conclude that ferret tracheal mucosa can release a factor which inhibits the contractile responses to cholinergic nerve stimulation. The release of this factor can be blocked to a major part by indomethacin and the factor can be transferred from a donor to a recipient preparation.
