MCDOLE, T.S.**; MURRAY, J.A.; CAIN, S.D.; Friday Harbor Labs, WA; Friday Harbor Labs, WA; Friday Harbor Labs, WA and Univ. of Central Arkansas, Conway: Neuronal Control of Mucociliary Interactions in Tritonia diomedea
Mucociliary interactions serve important functions in nearly all animals, yet little is known about the underlying neural and endocrine mechanisms that regulate and coordinate these two activities. In the sea slug Tritonia diomedea, crawling behavior is dependent upon the coordination and control of mucociliary activity. Previously, immunolabeling techniques and behavior experiments have shown that several cilio-regulatory neurotransmitters are widely distributed throughout the pedal (foot) epithelium of T. diomedea. One of these transmitters, acetylcholine, appears to be primarily located in regions of the pedal epithelium that also contain large numbers of mucosecretory glands (S. Cain, pers. comm.) and therefore might coordinate ciliary beating and mucus secretion. Here, we tested the hypothesis that acetylcholine is acting in a concentration dependent manner on both ciliary beat frequency and muco-secretory glands to directly regulate mucus secretion. Vibratome sections of pedal epithelium from T. diomedea were placed in a flow-through chamber mounted on a compound microscope and exposed to 1mM and 10mM acetylcholine. Our results indicate that the acetylcholine causes an increased rate of mucus secretion within T. diomedea foot tissue (p < 0.05; Student�s T-test). To test if this increase was a non-specific effect of altered ciliary beat frequency rather than a direct effect of acetylcholine application, we also measured mucus secretion caused by the application of serotonin. Serotonin has been shown to increase cilary beat frequency in T. diomedea, but is not present around the mucus glands in the foot epithelium. In this experiment, we found no effect of serotonin on mucus secretion. Our combined results indicate that ciliary beat frequency and mucus secretion can be regulated by the same extracellular messengers (e.g. Ach), but that the two mechanisms are not always coupled (e.g. 5-HT).
