P3.16 Friday, Jan. 6 Study of Octopamine in Bivalves WELSH, C.*; HOQUE, R.; IKOTUN, I.; JEAN LOUIS, A; CATAPANE, E.J.; CARROLL, M.A.; Medgar Evers College, Brooklyn, NY; Medgar Evers College, Brooklyn, NY; Medgar Evers College, Brooklyn, NY; Medgar Evers College, Brooklyn, NY; Medgar Evers College, Brooklyn, NY; Medgar Evers College, Brooklyn, NY firstname.lastname@example.org
Octopamine (OA), a biogenic amine first identified in octopus, is well studied in arthropods and gastropods. Its presence and actions have rarely been reported in bivalves. Previously, we identified OA in ganglia, gill, palps and hemolymph of the oyster Crassostrea virginica (order Osteoida) and found it a cardio-acceleratory agent. Here we examined the presence and effects of OA in Mercenaria mercenaria and Mytilus edulis. Amines were measured by HPLC and spectrofluorometry with an isocratic, ion-pairing Gemini 5µ C18 column. Clam and mussel heart preparations were prepared in situ by connecting ventricles to isotonic transducers with a small stainless steel hooks. Heart rate was monitored with a Narco Systems Physiograph. The results show OA present in ng amounts, along with serotonin, dopamine and norepinephrine, in the cerebral, visceral and pedal ganglia, as well as the gill, palps, heart and foot. Mussel and clam basal heart rates averaged 12 and 8 beats/min, respectively. Superfusion of OA (10-6-10-3 M) raised mussel heart rate by 80%, but reduced clam heart rate by 50%. The actions of OA were prevented by the OA antagonist phentolamine. The study identifies OA in the nervous system and innervated organs of two additional bivalve orders, Mytilorida and Veneroida, and demonstrates OA has cardio-acceleratory properties similar to C. virginica in M. edulis,but cardio-inhibitory properties in M. mercenaria. The different result in clam appears at first to be confusing, but Veneroida hearts are well know to respond differently to drugs and stimulations compared to other bivalve orders. This work was supported by grants 2R25GM0600309 of the Bridge Program of NIGMS, 0516041071 of NYSDOE and 0622197 of the DUE Program of NSF.