Meeting Abstract
P3.94 Thursday, Jan. 6 Study of Serotonin and Dopamine Post-Synaptic Receptor Mechanisms in the Bivalve Mollusc Crassostrea virginica ADAMS, T*; BEAUBRUN, D; NELSON, M; CARROLL, M.A.; CATAPANE, E.J.; Medgar Evers College; Kingsborough Community College; Medgar Evers College; Medgar Evers College; Medgar Evers College catapane@mec.cuny.edu
Lateral cilia of gill of Crassostrea virginica are controlled by serotonergic-dopaminergic nerves from their ganglia. Serotonin (HT) increases, dopamine (DA) decreases cilia beating rates. Previous work showed increasing cilia beating rates depolarizes the cell. Applying DA or 20 Hz ES decreases beating rates and repolarizes the membrane. The post-synaptic HT and DA responses are G-protein linked metabotrophic mechanisms involving activation or inhibition of adenylcyclase and changes in ion channel conductance. We studied the ions involved in generating the post-synaptic responses by observing membrane potentials of lateral cells using DIBAC, a voltage sensitive fluorescent dye, while measuring cilia beating rates. We used artificial sea water with ion replacements based on Formulae and Methods VI, Marine Biological Labs, Woods Hole, MA. Stimulating the branchial nerve at 5 Hz increased cilia beating rates and caused prolonged increased fluorescence, indicative of membrane depolarization. Stimulating at 20 Hz after exciting cilia decreased beating rates and repolarized the membrane. Potassium free salt water reduced the response to 5 and 20 Hz ES. The same was seen with sodium free salt water. No differences were seen with calcium free salt water, but it should be kept in mind that cells contain sequestered calcium that may be sufficient to initiate responses when external calcium is low. The study shows correlation between changes in membrane potential of lateral ciliated cells and beating rates of the cilia, with the activity of effector channels which change ionic fluxes. It provides insights into the HT and DA post-synaptic receptor mechanisms in the gill of C. virginica.
