EFFECTS OF CARDIOACTIVE PEPTIDES ON MYOCARDIAL CAMP LEVELS IN THE SNAIL HELIX-ASPERSA

Several cardioactive peptides from the pulmonate snail Helix aspersa w ere tested for their effects on myocardial cAMP levels, but only the f amily of small cardioactive peptides (SCPs) were clearly effective. SC P increased cAMP in a dose dependent manner; the time course was phasi c. The structure-activity relations of this effect were examined with a set of 3 synthetic analogs having characteristics, at the carboxyter minal, of both the SCPs and FMRFamide-related peptides. The adenylate cyclase activator forskolin mimicked the mechanical effect of SCPs on the heartbeat. We conclude that the effect of SCPs on the Helix heart may he mediated by cAMP. (C) 1997 Elsevier Science Inc.