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Dual actions of octopamine on heart rate of Crassostrea virginica (1169.1)
Author(s) -
Jean Louis Addy,
Carroll Margaret,
Catapane Edward
Publication year - 2014
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.28.1_supplement.1169.1
Subject(s) - heart rate , octopamine (neurotransmitter) , chemistry , medicine , chronotropic , bradycardia , endocrinology , pharmacology , receptor , blood pressure , serotonin
Octopamine (OA) is well studied in arthropods. OA’s presence and functions have rarely been reported in bivalves. Previously we found OA present in ganglia and tissues of the oyster Crassostrea virginica. OA was cardio‐acceleratory when applied in situ to animals but cardio‐inhibitory when applied to isolated hearts. We hypothesize the divergent results of OA on heart rate is due to separate actions of OA on visceral ganglia (VG) compared to isolated hearts. We applied OA to VG of animal preparations, with and without transecting the cardiac nerve. We also tested OA on isolated hearts and ventricular muscle strips. We found average basal heart rate of animal preparations was 15 beats/min. Superfusing OA (10 ‐6 ‐ 10 ‐3 M) onto animal or VG preparations caused dose‐dependent increases of up to 70%. Applying OA to isolated hearts or heart strips decreased rates to 0. The OA antagonist metoclopramide produced a dose‐dependent blockage of OA actions on animals and heart strips. In animals transecting the cardiac nerve prevented the cardio‐acceleratory effects of OA. The study shows OA affects heart rate in 2 fashions depending on site of application, inhibitory when applied to isolated heart or acceleratory when applied to the animals or VG. At the VG, OA may be stimulating cardio‐acceleratory neurons innervating the heart. Grant Funding Source : Nih‐2R25GM06003, NYSE 0516041171, NSF‐0622197