Polypeptide secretion from the eye of Aplysia californica

The possibility of neurosecretory activity by the eye of Aplysia californica has been suggested by morphological findings. An investigation was conducted to determine if evidence for the release of macromolecular material labeled with radioactive amino acids could be obtained. Depolarization of the eye by superfusion with medium containing an elevated potassium concentration resulted in a significant increase of labeled macromolecular material in the superfusate. This potassium-induced release could be blocked by reduction of the calcium concentration in the superfusing medium. The locus of release appears to be the eye proper and not to involve the optic nerve.