Meeting Abstract
The smooth muscle contractility 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. The goal of this project is to determine the effects of other FaRPs on the contractile activity of the crop-gizzard of L. terrestris by exploring the importance of amino acid substitutions and sequence extensions to the tetrapeptide core. 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. FMRFamide and APKQYVRFamide both caused concentration-dependent decreases in contraction amplitude, with FMRFamide having a threshold of 10-8 and APKQYVRFamide having a threshold of 10-6. YMRFamide also caused a concentration-dependent decrease in amplitude equipotent to APKQYVRFamide. FVRFamide and YVRFamide both caused a decrease in amplitude with a threshold of 10-8 followed by an increase in activity at higher concentrations. This indicates the presence of phenylalanine in the fourth position from the C-terminus is more important than the valine substitution. PAKHYVRFamide caused a concentration-dependent decrease in contraction amplitude with a threshold of 10-8. AGAYVRFamide caused a decrease in amplitude with a threshold of 10-8 followed by an increase in activity at higher concentrations. This indicates that lysine and glycine might play a role in determining peptide activity, while proline may determine potency.
