Meeting Abstract

P1.130  Sunday, Jan. 4  The Systematic Effects of Neurochemicals on the Alimenry Canal of the Earthworm Lumbricus terrestris KLOHR, RC; KRAJNIAK, KG*; Southern Illinois Univ. Edwardsville; Southern Illinois Univ. Edwardsville rklohr@siue.edu

In this study we examined the effects FMRFamide and acetylcholine on each individual segment of the alimentary canal. Each region was carefully dissected, attached to a transducer and suspended in a worm saline tissue bath. A series of applications of these drugs were administered at concentrations (1 pM to 10 M), and the percent change in amplitude and rate were measured and recorded. In the pharynx neither acetylcholine nor FMRFamide caused reproducible data. Treatment of the esophagus with FMRFamide elicited an excitatory response in amplitude with a concentration (0.01 to 1 nM) and a decrease in amplitude at concentration (10 nM to 1 M). The esophagus showed no change in rate except at 100 nM FMRFamide when it was excitatory in each trial. The crop and gizzard, examined separately, each showed a concentration dependant excitatory reaction in both rate and amplitude to increasing concentrations of FMRFamide (1 nM to 10 M). The same peptide applied to the intestine had an inhibitory effect in amplitude (0.01 nM to 1 M) with no change in rate. Acetylcholine applied to the esophagus caused a biphasic response that was excitatory in amplitude at low concentrations (0.01 to 0.1 nM) and an inhibitory at moderate concentrations (1 to 10 nM) followed by another excitatory response at high concentrations (100 nM) before becoming inhibitory again. The rate showed no change throughout the experiments until the neurotransmitter eliciting an excitatory response at higher concentrations (100 nM to 1 M). The response to acetylcholine of the crop and gizzard was excitatory for both amplitude and rate with a threshold of 10 nM. The intestine showed an overall inhibitory effect when acetylcholine was applied.