The peptide FMRFamide activates a divalent cation-conducting channel in heart muscle cells of the snail Lymnaea stagnalis.
1. Isolated Lymnaea stagnalis heart ventricle cells contain cation-conducting channels with properties characteristic of Ca2+ channels. These channels, which carry inward Na+ currents in the absence of Ca2+, are activated by the molluscan cardioactive peptides FMRFamide and FLRFamide, and are blocked by Co2+ ions. 2. FMRFamide also activated inward Ba2+ currents at the cell's resting potential. These currents, which were also blocked by Co2+ ions, reversed at a membrane potential of +70 mV. 3. Both sodium and barium currents were initiated when the peptides were applied to the cell outside of the patch pipette indicating that a secondary messenger is likely to be involved in the FMRFamide response.
Ottawa-Carleton Institute of Biology, Carleton University, Ontario, Canada.
B L
BL
Brezden
P R
PR
Benjamin
D R
DR
Gardner
D000818:Animals; D001464:Barium / Q000502:physiology; D002118:Calcium / Q000502:physiology; D015220:Calcium Channels / Q000187:drug effects* / Q000502:physiology; D019835:FMRFamide; D006321:Heart / Q000502:physiology*; D007447:Invertebrate Hormones / Q000494:pharmacology*; D008195:Lymnaea / Q000502:physiology*; D009206:Myocardium / Q000166:cytology; D009479:Neuropeptides / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D012964:Sodium / Q000502:physiology
D015220:Calcium Channels; D007447:Invertebrate Hormones; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D001464:Barium; D019835:FMRFamide; D012964:Sodium; D002118:Calcium