Meeting Abstract
P2.123 Sunday, Jan. 5 15:30 The Effects of FMRFamide and its Related Peptides on the Isolated Crop-Gizzard of the Earthworm Lumbricus terrestris. CORNWELL, F.J.*; KRAJNIAK, KG; Southern Illinois Univ. Edwardsville; Southern Illinois Univ. Edwardsville fcornwe@siue.edu
The contractile activity of the smooth muscle of L. terrestris can be regulated by a variety of neurotransmitters, including the family of FMRFamide-related peptides (FaRPs). Previously we used the recently identified earthworm FaRP, APKQYVRFamide, to explore the effects of FaRPs on the crop-gizzard of L. terrestris. Since valine is substituted for methionine in the tetrapeptide core of the earthworm peptide we decided to determine the importance of this substitution using tetrapide sequence FVRFamide. The crop-gizzard was isolated and suspended inside of a tissue bath composed of worm saline. Contractions were recorded using a Grass force transducer, and the data was displayed utilizing Iworx Labscribe 2. Increasing concentrations of each peptide were applied and allowed to take effect. The changes in activity were used to create log-dose response curves. FVRFamide caused a decrease in amplitude with a threshold of 10-8 followed by an increase in activity at higher concentrations. APKQYVRFamide caused a concentration dependent decrease in contraction amplitude with a threshold of 10-6 M, while FMRFamide caused the same response with a threshold of 10-8 M. These results show that the valine substitution does not change the threshold value for decreasing the amplitude and thus the receptor readily binds the two peptide sequences. We are currently exploring the effects of other substitutions found in worm peptides.
