Novel peptides

A peptide of any one of (a) to (e) below or a pharmaceutically acceptable salt thereof:

• (a) a peptide comprising the amino acid sequence of any one of SEQ ID NOS:
• 1 to 4, 28 and 29 (but excluding peptides comprising the amino acid sequence of SEQ ID NOS:
• 9, 30, 31, 32 or 33);
• (b) a peptide comprising an amino acid sequence with substitution, deletion, or addition of one to five amino acids in the amino acid sequence of any one of SEQ ID NOS:
• 1 to 4, 28 and 29, wherein the peptide has an activity of increasing the intracellular calcium ion concentration of cardiac or vascular cells;
• (c) a peptide comprising an amino acid sequence having 90% or higher homology to the amino acid sequence of any one of SEQ ID NOS:
• 1 to 4, 28 and 29, wherein the peptide has an activity of increasing the intracellular calcium ion concentration of cardiac or vascular cells;
• (d) a peptide represented by the following formula (I) (but excluding peptides comprising the sequences of SEQ ID NOS:
• 14 to 16),
• Z1-A-Z2 (I)
• (wherein, Z1 represents a hydrogen atom or a peptide residue of any sequence comprising one to eleven amino acids, A represents a peptide residue comprising the amino acid sequence of SEQ ID NO:
• 17, and Z2 represents an amino group or a peptide residue of any sequence comprising one to 38 amino acids);
• and
• (e) a peptide represented by the following formula (II)
• R1—B—R2 (II)
• (wherein, R1 represents a hydrogen atom, substituted or unsubstituted alkanoyl, substituted or unsubstituted aroyl, substituted or unsubstituted heteroarylcarbonyl, substituted or unsubstituted alkoxycarbonyl, substituted or unsubstituted aryloxycarbonyl, or substituted or unsubstituted heteroaryloxycarbonyl;
• R2 represents hydroxy, substituted or unsubstituted alkoxy, or substituted or unsubstituted amino;
• and B represents a peptide residue of the peptide of any one of the above-mentioned (a) to (d)).