Functional expression of the rat heart I Na+ channel isoform Demonstration of properties characteristic of native cardiac Na+ channels

Abstract
We describe the expression of functional Na+ channel in Xenopus oocytes injected with cRNA transcribed from the rat heart 1 cDNA clone. The expressed rat heart 1 Na+ currents show kinetic properties and resistance to tetrodotoxin and saxitoxin which are characteristic of native cardiac Na+ currents. The primary amino acid sequence of the rat heart 1 α-subunit is therefore sufficient for expression of of tetrodotoxin resistance, and the rat heart 1 clone is likely to account for the tetrodotoxin-resistant phenotype of cardiac and denervated skeletal muscle.