A comparative study of the adrenergic innervation of the teleost heart

An adrenergic cardiac innervation has been found in the following teleost species:Platycephalus bassensis (Platycephalidae);Atopomycterus nicthemerus (Diodontidae);Aracana ornata (Ostraciontidae);Torquiginer glaber (Tetraodontidae);Aldrichetta forsteri (Mugilidae);Anguilla australis occidentalis (Anguillidae). In contrast, no evidence for an adrenergic cardiac innervation was found in the pleuronectid, Rhombosolea tapirina. Fluorescence histochemical studies indicated that adrenergic nerves in the sinus venosus and atrium entered via the vagus, whereas those to the ventricle passed mainly along the coronary vasculature. No fluorescent nerves were observed in the heart of Rhombosolea. Transmural stimulation of these adrenergic nerves increased the force of beat in the atrium and ventricle of Platycephalus, Atopomycterus and Aracana, and in the atrium only of Torquiginer, Aldrichetta and Anguilla. In addition stimulation of the abdominal vagus nerve in the presence of hyoscine increased the force of beat and heart rate in spontaneously beating sinus-atrium preparations of all species except Rhombosolea. Applied catecholamines increased the force of beat and heart rate in the spontaneously beating heart of all species including Rhombosolea.