Protein kinase inhibitors do not block the expression of established enhancement in identified Hermissenda B-photoreceptors.

One-trial conditioning of Hermissenda produces short- and long-term enhancement of generator potentials in identified type B-photoreceptors. The induction of short-term enhancement is blocked by kinase inhibitors and down-regulation of protein kinase C. We now report that established short- and long-term enhancement produced by one-trial conditioning is not reversed by the kinase inhibitors H-7 or sphingosine. These results indicate that persistent protein kinase C activity is not required in the maintenance or expression of enhancement.