title: Peptidergic regulation of muscle movements in a prosobranch mollusc, Rapana thomasiana.
abstract: Peptidergic regulation of the contraction of radula muscles and the heart beat in a prosobranch mollusc, Rapana thomasiana was investigated. In the radula muscles, FMRFamide-related peptides were suggested to act on presynaptic sites to enhance their contraction elicited by nerve stimulation, possibly by increasing the release of a main transmitter. A catch-relaxing peptide (CARP) was demonstrated to depress the contraction by acting on postsynaptic sites. In the heart, FMRFamide enhanced the amplitude and frequency of the beat, whereas CARP depressed it. Immunohistochemical studies of the buccal ganglia have revealed that FMRFamide- and CARP-like immunoreactive neurons are distributed in the same region, indicating a possible coexistence of the both peptides. In the visceral ganglia, on the contrary, coexistence of FMRFamide and CARP was not observed. FMRFamide- and CARP-like immunoreactivities were also detected in the nerve fibers in the radula muscles and the atria. The present results show that FMRFamide- and CARP-like peptides are involved in the regulation of the contraction of radula muscles and the heart beat.
authors.affiliation: Physiological Laboratory, Faculty of Integrated Arts and Sciences, Hiroshima University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kobayashi
authors.forename: M F
authors.initials: MF
authors.lastname: Sakata
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019835:FMRFamide; D005724:Ganglia / Q000502:physiology; D008969:Molecular Sequence Data; D008974:Mollusca / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D009200:Myocardial Contraction / Q000502:physiology; D009474:Neurons / Q000502:physiology; D009479:Neuropeptides / Q000737:chemistry / Q000502:physiology*; D009842:Oligopeptides / Q000737:chemistry / Q000502:physiology
chemical_list: D009479:Neuropeptides; D009842:Oligopeptides; C054127:catch-relaxing peptide (Mytilus); D019835:FMRFamide; C066148:phenylalanyl-leucyl-arginyl phenylalaninamide