Cardioactive peptides isolated from the brain of a Japanese octopus, Octopus minor

Octopus cardioactive peptides (Ocp-1: Gly-D-Phe-Gly-Asp, and Ocp-3: Gly-Ser -Trp-Asp) were isolated from brain extracts of the octopus, Ocropus minor, using the isolated systemic heart as a bioassay. These peptides showed both positive chronotropic and inotropic effects on the heart. The stereoisomer s at position 2 were also isolated, but their activities were only 1/10(3)- 1/10(4) those of the corresponding isomers. The presence of the peptides in the systemic heart was confirmed by time-of-flight mass spectrometry (MS) and tandem MS analysis. The results suggested that Ocp-1 and Ocp-3 might be involved in excitatory control of the octopus cardiovascular system as neu ropeptides and/or neurohormones. (C) 2000 Elsevier Science Inc. All rights reserved.