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Mar. Drugs 2011, 9(11), 2409-2422; doi:10.3390/md9112409
Article

Tetrodotoxin Sensitivity of the Vertebrate Cardiac Na+ Current

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Received: 20 September 2011; in revised form: 2 November 2011 / Accepted: 10 November 2011 / Published: 21 November 2011
(This article belongs to the Special Issue Tetrodotoxin)
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Abstract: Evolutionary origin and physiological significance of the tetrodotoxin (TTX) resistance of the vertebrate cardiac Na+ current (INa) is still unresolved. To this end, TTX sensitivity of the cardiac INa was examined in cardiac myocytes of a cyclostome (lamprey), three teleost fishes (crucian carp, burbot and rainbow trout), a clawed frog, a snake (viper) and a bird (quail). In lamprey, teleost fishes, frog and bird the cardiac INa was highly TTX-sensitive with EC50-values between 1.4 and 6.6 nmol·L−1. In the snake heart, about 80% of the INa was TTX-resistant with EC50 value of 0.65 μmol·L−1, the rest being TTX-sensitive (EC50 = 0.5 nmol·L−1). Although TTX-resistance of the cardiac INa appears to be limited to mammals and reptiles, the presence of TTX-resistant isoform of Na+ channel in the lamprey heart suggest an early evolutionary origin of the TTX-resistance, perhaps in the common ancestor of all vertebrates.
Keywords: evolution of tetrodotoxin sensitivity; vertebrate animals; cardiac sodium current evolution of tetrodotoxin sensitivity; vertebrate animals; cardiac sodium current
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Vornanen, M.; Hassinen, M.; Haverinen, J. Tetrodotoxin Sensitivity of the Vertebrate Cardiac Na+ Current. Mar. Drugs 2011, 9, 2409-2422.

AMA Style

Vornanen M, Hassinen M, Haverinen J. Tetrodotoxin Sensitivity of the Vertebrate Cardiac Na+ Current. Marine Drugs. 2011; 9(11):2409-2422.

Chicago/Turabian Style

Vornanen, Matti; Hassinen, Minna; Haverinen, Jaakko. 2011. "Tetrodotoxin Sensitivity of the Vertebrate Cardiac Na+ Current." Mar. Drugs 9, no. 11: 2409-2422.


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