Reivindicaciones

1. Peptides of general formula R<1>-X<1>X<2>RESLAX<3>X<4>X<5>-R<2> (R<1>-SEQ ID NO: 2-R<2>), in which R1 is selected from hydrogen (H), arginine (R), acetyl (Ac), palmitoyl (Pal), Ac-R or Pal-R X<1> is selected from F, Y or W, X<2> is selected from T, S, C or M, X<3> is selected from A, G, V, L or I, X<4> is selected from I, G, A, V or L, X<5> is selected from E or D, and R2 is selected from OH, NH<2>, K-NH<2>, K(SF)-NH<2>, or KR-NH<2>, where SF indicates fluorescent probe. 2. The peptide according to claim 1, wherein R1 is selected from H, Ac or Pal. 3. The peptide according to claim 2, wherein R2 is selected from alkyl OH, NH<2>, K-NH<2>, K(SF)-NH<2>, or KR-NH<2>. 4. The peptide according to any of claims 1-3, which is selected from the group consisting of SEQ ID NO: 3, Pal-SEQ ID NO: 23-NH<2> and/or Pal-SEQ ID NO: 25-NH<2>. 5. The peptide according to any of claims 1-4, for use as a medicine. 6. The peptide according to claim 5, for use as a medicine in cardiac diseases. 7. The peptide according to claim 6, wherein the cardiac diseases belong to the group consisting of: ventricular arrhythmias associated with cardiac hypertrophy, cardiac insufficiency and/or hereditary syndromes secondary to mutations in the SCN5A or KCNJ2 genes resulting in the loss of function in the Nav1.5 or Kir2.1 channels. 8. The peptide according to claim 7, wherein the hereditary syndromes belong to the group consisting of: Brugada Syndrome, Progressive cardiac conduction defect syndrome and Andersen-Tawil syndrome. 9. A cDNA molecule encoding the peptide described in SEQ ID NO: 3, Pal-SEQ ID NO: 25-NH<2> or Pal-SEQ ID NO: 25-NH<2>. 10. The cDNA molecule according to claim 9, consisting of SEQ ID NO: 5, SEQ ID NO: 27 or SEQ ID NO: 28. 11. The cDNA molecules according to any of claims 9-10, for use as a medicine. 12. The cDNA molecules according to claim 11, for use as a medicine in cardiac diseases. 13. The cDNA molecules according to claim 12, wherein the cardiac diseases belong to the group consisting of: ventricular arrhythmias associated with cardiac hypertrophy, cardiac insufficiency and/or hereditary syndromes secondary to mutations in the SCN5A or KCNJ2 genes resulting in the loss of function in the Nav1.5 or Kir2.1 channels. 14. The cDNA molecules according to claim 13, wherein the hereditary syndromes belong to the group consisting of: Brugada Syndrome, Progressive cardiac conduction defect syndrome and Andersen-Tawil syndrome. 15. A vector including a cDNA molecule as defined in any of claims 9-10. 16. A eukaryotic or prokaryotic cell containing any of the peptides, cDNA molecules or vectors as defined in claims 1-4, 9-10, 15. 17. A pharmaceutical composition comprising a peptide as defined in any of claims 1-4 and a pharmaceutically acceptable excipient. 18. A pharmaceutical composition comprising the molecule of any of claims 9-10 and a pharmaceutically acceptable excipient. 19. A pharmaceutical composition comprising the vector and/or the cell of any of claims 15-16 and a pharmaceutically acceptable excipient. 20. The pharmaceutical composition according to any of claims 17-19, for use in the prevention and/or treatment of cardiac diseases. 21. The pharmaceutical composition according to claim 20, wherein the cardiac diseases belong to the group consisting of: ventricular arrhythmias associated with cardiac hypertrophy, cardiac insufficiency and/or hereditary syndromes secondary to mutations in the SCN5A or KCNJ2 genes resulting in the loss of function in the Nav1.5 or Kir2.1 channels. 22. The pharmaceutical composition according to claim 21, wherein the hereditary syndromes belong to the group consisting of: Brugada Syndrome, Progressive cardiac conduction defect syndrome and Andersen-Tawil syndrome.