Meeting Abstract
Our lab has shown thatFMRFamide alters the contractions of the smooth muscle tissues in Lumbricus terrestris including the body wall. Recently new annelid FMRFamide-related peptides (FaRPs) have been identified, including tetrapeptides and N-terminally extended peptides, and therefore we decided to examine their effects on the body wall. A body wall strip without the ventral nerve cord was placed in a tissue bath and exposed to increasing concentrations of peptides. Mechanical contractions were recorded on a computer with a Grass force transducer attached to an Iworx A/D converter. FMRFamide increased amplitude with a threshold of 10-7 M and decreased rate with a threshold of 10-7 M. APKQYVRFamide increased amplitude with a threshold of 10-7 M and had a biphasic effect on rate, decreasing it at 10-9 M, and increasing it at 10-8 M. YMRFamide increased amplitude with a threshold between 10-8 and 10-7 M and decreased rate with a threshold of 10-8 M. AGAYVRFamide caused a biphasic change in amplitude, decreasing it at 10-9 M and increasing it between 10-8 and 10-7 M and a biphasic rate change, decreasing it at 10-9 M and increasing it at 10-8 M. YVRFamide increased amplitude with a threshold of 10-9 M and decreased rate with a threshold between 10-9 and 10-8 M. FVRFamide increased amplitude with a threshold of 10-9 M, but had no effect on rate. These data suggest that tetrapeptides and N-terminally extended YVRFamides may be acting on different receptors
