Myomodulin application increases cAMP and activates cAMP-dependent protein kinase in the accessory radula closer muscle of Aplysia

Abstract

Myomodulin A (MMA) application or stimulation of neuron B16, which releases MMA, increases cAMP levels in the accessory radula closer (ARC) muscle of Aplysia. MMA application also increases cAMP-dependent protein kinase (cAPK) activity in one subcellular compartment of the muscle. These results suggest that at least part of MMA's effects in this system are mediated via the cAPK signal transduction pathway. Since the effects of the small cardioactive peptides (SCPs) on ARC muscle contraction are similar to those of MMA, our results suggest that the convergent physiological effects of MMA and SCPB in this system may be due, in part, to the two peptide neuromodulators utilizing the same signal transduction pathway.