Effects of three anthozoan neuropeptides, Antho-RWamide I, Antho-RWamide II and Antho-RFamide, on slow muscles from sea anemones.
Antho-RWamide I (less than Glu-Ser-Leu-Arg-Trp-NH2) and Antho-RWamide II (less than Glu-Gly-Leu-Arg-Trp-NH2), the second and third anthozoan neuropeptides to be identified, both induced slow contractions of several endodermal muscles in four species of sea anemone. In a fifth species, Protanthea simplex, Antho-RWamide II, but not Antho-RWamide I, evoked contractions of body wall muscles. Isolated, trimmed sphincter muscle preparations of Calliactis parasitica contracted at a threshold concentration of 10(-9) mol l-1 Antho-RWamide II. Antho-RWamide II was more potent than Antho-RWamide I. Unlike the responses to Antho-RFamide (the first anthozoan neuropeptide described), these were simple contractions with no change in spontaneous activity. The Antho-RWamides did not excite electrical activity in any of the three known conducting systems (the through-conducting nerve net and the slow systems 1 and 2), indicating that they may be acting directly on endodermal muscles. Application of peptides to smooth muscle cells, isolated from the sphincter of C. parasitica, confirmed that Antho-RWamide I and II act directly on the muscle. We conclude that the Antho-RWamides may be neurotransmitters at some neuromuscular synapses in sea anemones.
McFarlane
I D
ID
Department of Applied Biology, University of Hull.
Anderson
P A
PA
Grimmelikhuijzen
C J
CJ
D000818:Animals; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000502:physiology; D009132:Muscles / Q000502:physiology*; D009479:Neuropeptides / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000502:physiology; D009842:Oligopeptides / Q000502:physiology*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D012615:Sea Anemones / Q000502:physiology*
D009479:Neuropeptides; D018377:Neurotransmitter Agents; D009842:Oligopeptides; C060288:4-pyroglutamyl-glycyl-arginyl-phenylalaninamide; C056018:Antho-RWamide I; C057541:Antho-RWamide II; D011761:Pyrrolidonecarboxylic Acid