A. Legrand, R. Bagnis
Jul 1, 1984
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Journal
Journal of molecular and cellular cardiology
Abstract
Maitotoxin is a substance extracted from a dinoflagellate and certain tropical poisonous fish. It is considered as the most potent marine toxin (50 times more potent than tetrodotoxin). In isolated mammalian atria, maitotoxin produces at low doses a positive inotropic effect not modified by reserpine pretreatment and suppressed by Mn2+ ions. In the anaesthetized cat, it induces cardiac arrhythmias and tachycardia leading to cardiac failure. On the other hand, maitotoxin strongly inhibits Na+-K+ ATP-ase from microsomes of cat and human kidneys. In a rat pheochromocytoma cell line, it has been shown to promote a norepinephrine release and an increase in Ca2+ influx. The purpose of this work is to study the effect of maitotoxin on action potential of isolated perfused rat heart to check the existence of a direct effect on the myocardium.