Meeting Abstract

P2.144  Monday, Jan. 5  The Effect of Cyclic Nucleotide Dependent Protein Kinase Activity on Swimming in Clione limacina WALTON, D.B.*; PIRTLE, T.J.; Abilene Christian University; Abilene Christian University dbw04a@acu.edu

Both serotonin and nitric oxide have been shown to increase swimming speed in reduced preparations of the pteropod mollusk Clione limacina. Additionally, isoliquiritigenin, an activator of guanylyl cyclase, has a similar effect as serotonin and nitric oxide in that it enhances swim frequency. On the other hand, forskolin, an activator of adenylyl cyclase, suppresses swimming. These results indicate that cGMP accelerates swimming while cAMP inhibits swimming. We hypothesize that the changes in swim frequency that occur with cGMP and cAMP are the result of their action on cyclic nucleotide dependent protein kinases. To test this hypothesis we applied H-9, an inhibitor of cyclic nucleotide activated kinases. Application of H-9 had a biphasic effect. Initially, within the first minute of application, H-9 increased swim frequency. A complete cessation of swim activity followed this initial enhancement. Furthermore, application of serotonin did not recover H-9 induced inhibition of swim activity. Our results indicate that the initial enhancement of swimming is a consequence of inhibition of cAMP-dependent protein kinase and that the termination of swimming that follows is a consequence of inhibition of cGMP- dependent protein kinase.