Studies of the characteristics, distribution and physiological role of a large cardioactive peptide in Lymnaea stagnalis. 
Large cardioactive peptide (LCP, heat-stable, mol.  wt greater than or equal to 1500) occurs in the ventricle and CNS, and in high concentrations in the auricle.  The LCP haemolymph concentrations in fed animals are ca.  35 times higher than those in starved snails.  The excitatory effects of LCP on auricle, ventricle and oesophagus are similar to those of some (putative) neurotransmitters.  LCP has no effects on the penis retractor muscle.  Its effects on the auricle are much more prolonged than those of the transmitters.  It is suggested that LCP is a neurohormone, which is transported to the auricle via the nervus intestinalis, and released in response to feeding stimuli.