<Tr> <Th> </Th> <Th> Current (I) </Th> <Th> α subunit protein </Th> <Th> α subunit gene </Th> <Th> Phase / role </Th> </Tr> <Tr> <Td> Na </Td> <Td> </Td> <Td> Na 1.5 </Td> <Td> SCN5A </Td> <Td> 0 </Td> </Tr> <Tr> <Td> Ca </Td> <Td> </Td> <Td> Ca 1.2 </Td> <Td> CACNA1C </Td> <Td> 0 - 2 </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> K 4.2 / 4.3 </Td> <Td> KCND2 / KCND3 </Td> <Td> 1, notch </Td> </Tr>

During the early repolarization and plateau phases of cardiac muscle