Aplysia cardioactive peptide (NdWFamide) enhances the L-type Ca2+ current of Aplysia ventricular myocytes

NdWFamide is a D-amino acid containing tripeptide purified from Aplysia heart. Although the cardioexcitatory action of NdWFamide is well established, little is known about how the excitatory action is induced. To examine the action of the peptide on the ion channels expressed in the Aplysia heart muscles, we carried out whole cell clamp experiments in the isolated Aplysia ventricular myocytes. We found that the high voltage-activated (HVA) Ca(2+) current of Aplysia ventricular myocytes is mostly a nifedipine-sensitive L-type current, and that the current was enhanced by NdWFamide via the activation of G proteins.