Methods and compositions for measuring biologically active natriuretic peptides and for improving their therapeutic potential

A method for detecting the presence or amount of one or more natriuretic peptides of interest in a sample, comprising:

• assaying said sample to provide an assay result related to the presence or amount of said natriuretic peptide(s) of interest in said sample, wherein said assay is performed under conditions selected to provide a detectable signal related to the presence or amount of an intact natriuretic peptide, and at least a 5-fold reduction in said signal from an equimolar amount of a fragment formed by removal of a portion of the intact natriuretic peptide.

A method for detecting the presence or amount of one or more natriuretic peptides of interest in a sample, comprising:

• assaying said sample to provide an assay result related to the presence or amount of said natriuretic peptide(s) of interest in said sample, wherein said assay result depends upon an antibody selected to specifically bind to a biologically active natriuretic peptide, wherein said specific binding is measured relative to a biologically inactive peptide formed by cleavage of at least one peptide bond of said biologically active natriuretic peptide.

A method of inhibiting degradation of a natriuretic peptide present in a system comprising a prolyl-specific DPP, comprising:

• administering one or more inhibitors of prolyl-specific DPP in an amount sufficient to inhibit degradation of the natriuretic peptide.

A method for increasing the level of natriuretic peptide function in a subject, comprising:

• administering one or more inhibitors of prolyl-specific DPP to said subject in an amount sufficient to inhibit degradation of the natriuretic peptide in said subject.

A pharmaceutical composition comprising one or more inhibitors of prolyl-specific DPP and one or more additional molecules selected from the group consisting of inhibitors of neutral endopeptidase and natriuretic peptides.