Meeting Abstract
P2.122 Sunday, Jan. 5 15:30 The Effects of FMRFamide on the Isolated Pharynx of the Earthworm MCKIBBEN, TP*; KRAJNIAK, KG; Southern Illinois Univ. Edwardsville; Southern Illinois Univ. Edwardsville tmckibb@siue.edu
Our laboratory has been examining the effects of FMRFamide-related peptides (FaRPs) on the digestive tract of the earthworm, Lumbricus terrestris. Many FaRP sequences have been isolated from annelids. The tetraptide FMRFamide previously has been shown to regulate the contractions of smooth muscle of the crop-gizzard. So we decided to examine the effects of FMRFamide on the pharynx preparation. The pharynx was removed from the animal, placed in a tissue bath filled with earthworm saline and attached to a force transducer. The force transducer was connected to a computer. We used IWorx software to record the contractions of the crop-gizzard. Increasing concentrations of FMRFamide were injected into the tissue bath and the resulting changes in contraction rate and amplitude were used to create log-dose response curves. The pharynx has complex contractile pattern that includes large contraction interspersed within regions of smaller contractions. We investigated the effects of FMRFamide on both the large and the small contractions accordingly. Prelimary results show that FMRFamide causes a slight decrease in contractile rate of the large contractions, but nothing significant. As for the amplitude of the large contractions a slight increase in amplitude is seen with a threshold concentration of 0.1 uM. The little contractions in contrast showed a much more significant response to FMRFamide. The rate of the smaller contractions increased in rate with a threshold concentration of 0.1 uM and then immediately returning to baseline for the rest of the experiment. The amplitude of the smaller contractions the rose to an average of 150 percent with a threshold concentration of 10 nM . These results show that FMRFamide does regulate the contractility of the pharynx. We are now examining the responses of the pharynx to the annelid peptide APKQYVRFamide and other worm FaRPs.
