Substance P in the regulation of mucociliary transport in the frog palate.

1. Mucociliary transport of carbon particles across the palate of anesthetized Rana pipiens was accelerated by electrical stimulation of the palatine nerve. 2. Transport was also accelerated by intracardiac injection of acetylcholine and of substance P in a dose-dependent manner. 3. Acceleration of transport by acetylcholine and by substance P was selectively blocked by atropine and by the substance P antagonist Spantide, respectively. 4. Acceleration of transport by nerve stimulation was blocked partially by atropine and by Spantide, and completely by the two administered concurrently. 5. It is concluded that nerve stimulation releases both acetylcholine and substance P or a similar neuropeptide. 6. Taken in conjunction with the literature, the data suggest that these substances are involved in the normal mechanism for stimulating mucociliary clearance of the palate in response to the presence of particles.