Meeting Abstract
P2.168 Saturday, Jan. 5 Effects of APKQYVRFamide and FMRFamide on the Earthworm Body Wall KRAJNIAK, K.G.*; KERSTEIN, K.W.; Southern Illinois Univ. Edwardsville; Southern Illinois Univ. Edwardsville kkrajni@siue.edu
Recently our laboratory identified APKQYVRFamide, the first earthworm FMRFamide related peptide. Since FMRFamide modulates the contractions of the isolated body wall of Lumbricus terrestris we decided to determine the effects of APKQYVRFamide. A 10 segment section of dorsal body wall anterior to the clitellum was removed, attached to a Grass force transducer, and suspended in a tissue bath. Mechanical contractions of the longitudinal muscles were recorded on a computer using Iworx Labscribe 2. The body wall was challenged with increasing concentrations of peptide and the resulting changes in contraction amplitude and rate were used to construct log-concentration response curves. APKQYVRFamide caused a large increase in frequency at 10-9 M. Between 10-8 and 10-6 M it caused a decrease in rate and at 10-5 M it caused an increase. For all concentrations of APKQYVRFamide the changes in amplitude remained in the negative range. At 10-8 M the peptide caused an increase in amplitude. FMRFamide caused a complex response with a large increase in frequency between 10-9 and 10-8 M. Between 10-7 and 10-5 M it caused a decrease in rate. FMRFamide caused a slight inhibition of amplitude between 10-9 and 10-7 M. Between 10-7 and 10-6 M there was a substantial increase in amplitude followed by an equally large decrease between10-6 and 10-5 M. Thus it appears that APKQYVRFamide, which is more potent than FMRFamide, may be involved in controlling body wall movements of the earthworm.
