Introduction Atrial natriuretic peptide (ANP), a 28 amino acid polypeptide, is mainly secreted from the atrium of the heart where it is stored in secretory granules as a 136 amino acid pro-hormone (1). Upon its secretion, which is induced by increases in atrial pressure and stretch, the pro-hormone is processed by a serine protease to the active 28 amino acids peptide. The peptide binds with high affinity to the membrane receptor guanylate cyclase GC-A, leading to increased intracellular cGMP levels (2). Increased ANP plasma level has been identified as predictors of cardiac dysfunction and prognosis in congestive heart failure and ischemic heart disease (3-5). Lower plasma levels of ANP will lead to sodium retention, and an increase in plasma volume, resulting in an increase blood pressure (6).
Principle of the Assay The AssayMax Rat ANP ELISA (Enzyme-Linked Immunosorbent Assay) kit is designed for detection of rat ANP in plasma, serum, tissue extract, and cell culture supernatants. This assay employs a quantitative sandwich enzyme immunoassay technique that measures rat ANP in less than 5 hours. A polyclonal antibody specific for rat ANP has been pre-coated onto a 96-well microplate with removable strips. The rat ANP in standards and samples is sandwiched by the immobilized antibody and biotinylated polyclonal antibody specific for ANP, which is recognized by a streptavidin-peroxidase conjugate. All unbound material is then washed away and a peroxidase enzyme substrate is added. The color development is stopped and the intensity of the color is measured.