Potassium channel modulators

A peptide (I) having intracellular potassium channel modulating activity and having a 28 amino acid sequence, as listed in SEQ ID No:

• 2, which is
• (N terminal group) (I) Met Ile Ser Ser Val Cys Val Ser Ser 1 5} Tyr Arg Gly Arg Lys Ser Gly Asn Lys 10 15 Pro Pro Ser Lys Thr Cys Leu Lys Glu Glu 20 25 (C terminal group)
• in which the cysteines are optionally linked via a disulphide bridge and wherein
• ______________________________________ Met represents L-methionine Ile represents L-isoleucine Ser represents L-serine Val represents L-valine Cys represents L-cysteine Tyr represents L-tyrosine Arg represents L-arginine Gly represents glycine Lys represents L-lysine Asn represents L-asparagine Pro represents L-proline Thr represents L-threonine Leu represents L-leucine Glu represents L-glutamic acid Nle represents L-norleucine Gln represents L-glutamine, ______________________________________
• the N-terminal group is an amino or substituted amino group, and the C-terminal group is --OH or --OC.sub.1 -C.sub.6 alkyl or a --NH.sub.2, --NHC.sub.1 -C.sub.6 alkyl or --N(C.sub.1 -C.sub.6 alkyl).sub.2,
• or a variant thereof in which, independently, 1-Met is replaced by 1-Nle, or Glu is replaced by Asp, or 17-Asn is replaced by 17-Gln, or one or more Arg or Lys residues are interchanged,
• with the proviso that excluded is the 13-Lys variant where 13-Arg is replaced by 13-Lys in which the cysteines are not linked via a disulphide bridge,
• and wherein a substituted amino group is a mono- or di-C.sub.1 -C.sub.6 alkylamino group or a C.sub.2 -C.sub.7 alkyl-, aryl-, aralkyl- or heteroaralkyl-carbonylamino group, in which aryl is phenyl or naphthyl and heteroaryl is an aromatic mono- or bi-cyclic group having 5 to 10 ring atoms, at least one of which is a heteroatom, selected from O, N or S, which may be optionally substituted with one or more C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkoxy, hydroxy, halo, nitro, amino, C.sub.1 -C.sub.6 alkylamino, acylamino, carboxy, C.sub.1 -C.sub.6 alkoxycarbonyl, mercapto, haloC.sub.1 -C.sub.6 alkyl and aminocarbonyl groups.