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Octopamine has a dual effect on heart rate of Crassostrea virginica
Author(s) -
Hoque Ruma,
Louis Addy Jean,
Carroll Margaret A.,
Catapane Edward J.
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.714.1
Subject(s) - octopamine (neurotransmitter) , heart rate , hemolymph , endocrinology , medicine , phentolamine , crassostrea , chemistry , antagonist , biology , receptor , oyster , blood pressure , biochemistry , serotonin , ecology
Octopamine (OA) is well studied in arthropods and gastropods being a neurotransmitter and hormone. Its functions have rarely been reported in bivalves. We identified OA in cerebral and visceral ganglia (VG), gill, palps and hemolymph of the oyster Crassostrea virginica. We found OA is cardio‐acceleratory when applied to animals and speculated it is a neuro or endocrine agent. We tested OA on heart rate of C. virginica by applying OA to VG of animals ( in situ) or isolated hearts. Average heart rate of animal preparations was 5.5 beats/min. Superfusion of OA (10 −6 –10 −3 M) to VG increased it to 9.3 in a dose dependent manner. Average rates of isolated heart preparations was 13.4. Bath applications of OA (10 −6 –10 −3 M) decreased it to 0. Actions of OA were prevented by the OA antagonist phentolamine. The study shows OA affects heart rate in 2 different fashions depending on site of application. It decreases heart rate when applied to isolated heart, but increases it when applied to VG. A possible explanation for the divergent results is OA is activating different receptors in the different locations. Superfusing OA to VG causes it to stimulate different neurons at simultaneously. The end result is due to the nerves being stimulated, which is not what happens in an animal's normal physiological actions. Under normal conditions OA would be discretely released to stimulate discrete neuronal circuits at a particular time.