전자저널 > 전자저널 > Effects of cardiovascularly acting neuroendocrine agents on heart beatings of Pacific oyster Crassostrea gigas

Effects of cardiovascularly acting neuroendocrine agents on heart beatings of Pacific oyster Crassostrea gigas

Kwan Ha Park

Department of Aquatic Life Medicine, College of Ocean Science & Engineering, Kunsan National University, Miryong-dong San 68, Kunsan City, Chonbuk, Korea

Because it is known that bivalve hearts contain various modulatory systems activated by neuroendocrine substances, it was examined whether different classes of endogenous and synthetic drugs of neuroendocrinological importance can influence cardiac functions of the Pacific oyster Crassostrea gigas. Cholinergically active agents acetylcholine and carbachol increased heart rates while diminishing cardiac contractility. Adrenergically active substances norepinephrine (NE) and epinephrine (Epi) also induced heart rate increase and contractility decrease. An α1-adrenergic receptor-selective agonist phenyephrine (PE) failed to modulate either parameter. The Epi-induced heart rate increase and contractile depression were both blocked significantly by non-selective β1/β2-adrenergic antagonist propranolol. A β1-selective antagonist atenolol prevented Epi-induced heart rate decrease but not the contractile depression, suggesting possible β2 receptors for Epi-induced contractile depression. The three autacoids examined exerted discrete responses: histamine increased heart rate and depressed contraction; γ-amino-butyric acid increased both parameters; serotonin failed to change either parameter. The 5 piscine anesthetic agents examined, MS-222, benzocaine, quinaldine, urethane, pantocaine and pentobarbital, all failed to influence the cardiac function of oysters. Collectively, activities of neuroendocrinologically acting agents in mammals showed unexpected and distinct activities from those accepted based on mammalian cardiovascular systems. These results obtained from substances of different physiological can serve as a basis for understanding neuroendocrine control of the heart function in Pacific oyster.

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