. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. REPORTS FROM MBL GENERAL SCIENTIFIC MEETINGS 353 Cardioregulatory Peptides in Limulus: Effects of Fl, F2 and an Endogenous FMRFaniide-like Peptide on the Neurogenic Heart James R. Groome (Biology Department, Utah State University, Logan, UT 84322-5305) and Winsor H. Watson III The neurogenic heart of the horseshoe crab, Limulus poly- phcnuts. has been used as a model system with which to study the cellular and molecular mechanisms underlying specific ac- tions of peptide and amine neuromodulators (1). The peptide Phe-Met-Arg
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. REPORTS FROM MBL GENERAL SCIENTIFIC MEETINGS 353 Cardioregulatory Peptides in Limulus: Effects of Fl, F2 and an Endogenous FMRFaniide-like Peptide on the Neurogenic Heart James R. Groome (Biology Department, Utah State University, Logan, UT 84322-5305) and Winsor H. Watson III The neurogenic heart of the horseshoe crab, Limulus poly- phcnuts. has been used as a model system with which to study the cellular and molecular mechanisms underlying specific ac- tions of peptide and amine neuromodulators (1). The peptide Phe-Met-Arg-Phe-NH2 (FMRFamide), or an analog, has been proposed as a candidate cardioregulator in Limulus. FMRFam- ide-like peptides have been detected in insects and crustaceans (2), and FMRFamide-like immunoreactivity has been detected in the Limulus CNS and cardiac ganglion (3). Although FMRFamide itself is cardioactive in the horseshoe crab only at high (>10 5 M) doses, a potent endogenous cardioactive FMRFamide-like peptide has been reported to occur in Limulus (4). We have characterized the action of this native FMRFamide- like peptide on the neurogenic heart of the horseshoe crab, and have compared these effects with those of synthetic identified analogs. A factor partially purified from the Limulus prosomal CNS produces characteristic excitatory chronotropic and inotropic effects when applied to the intact Limulus heart preparation (Fig. 1). This factor also produces FMRFamide-like contracture of the Busvcon radula protractor muscle, a characterized bioassay for the peptide (5). The peptide character of this factor was de- termined by enzymatic degradation (loss of biological activity) with trypsin or pronase. A single peak of cardioactivity is detected by high performance liquid chromatography of the prosomal extract, eluting at 38% acetonitrile on a linear gradient of 66% to 48% in 70 min. The chronotropic effect of this peptide factor on the intact heart is probably a resul
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
