Medaka as a model for ECG analysis and the effect of verapamil

Publication date: May 2018Source: Journal of Pharmacological Sciences, Volume 137, Issue 1Author(s): Manabu Yonekura, Nami Kondoh, Chong Han, Yuichi Toyama, Takayoshi Ohba, Kyoichi Ono, Shirou Itagaki, Hirofumi Tomita, Manabu MurakamiAbstractThe heart of the medaka, a small fish native to East Asia, has electrophysiological aspects similar to mammalian hearts. We found that the heart rates of medaka were more similar to humans than mice or rats. Medaka exhibited similar electrocardiogram patterns to those of humans, suggesting a similarity in cardiac impulse formation and propagation. Their hearts also exhibited similar responsiveness to verapamil, a calcium channel antagonist; atropine, a parasympathetic nerve blocker; propranolol, a sympathetic β-adrenergic blocker; and isoproterenol, a sympathetic β-adrenergic agonist. We successfully analyzed action potentials and cardiac contractile forces in vivo. Verapamil affected action potential duration and reduced heart rate, suggesting the importance of voltage-dependent calcium channels in determining the heart rhythm of medaka. We also analyzed the expression of the voltage-dependent calcium channel β2 subunit, which participates in channel formation in cardiac myocytes, and found that splice variant type-2 was the only major transcript in the heart. Our results indicate that medaka could be an appropriate animal model for studying cardiovascular pharmacology.
Source: Journal of Pharmacological Sciences - Category: Drugs & Pharmacology Source Type: research