THE ANTHOZOAN NEUROPEPTIDE ANTHO-RWAMIDE-I MODULATES CA2-ANEMONE MYOEPITHELIAL CELLS( CURRENT IN SEA)

The anthozoan neuropeptide Antho-RWamide I (<Glu-Ser-Leu-Arg-Trp-NH2) excites contraction of endodermal muscles in sea anemones. Single elec trode voltage clamp recordings from semi-intact preparations of endode rmal myoepithelial cells reveal that Antho-RWamide I increases an inwa rd Ca2+ current. Evidence for the involvement of a Ca2+ current in con traction was supported by the observation that Cd2+ abolished spontane ous contractions and reduced inward current. Contractions and inward c urrents induced by Antho-RWamide I were not, however, completely aboli shed in the presence of Cd2+. We conclude that Antho-RWamide, a putati ve neurotransmitter at sea anemone smooth muscle, acts by opening, eit her directly or indirectly, Ca2+ channels in the muscle membrane.