Prepro-atrial natriuretic factor (26-55) (human) (NT-pro-ANP (1-30)) is one of four peptide hormones derived from the atrial natriuretic prohormone. It is also known as long acting natriuretic peptide. The peptide has potent vasodilatory properties equal to atrial natriuretic factor. Vasodilation is associated with a 4-5 fold increase in cyclic GMP levels due to activation of particulate guanylate cyclase activity. Like prepro-atrial natriuretic factor (56-92) and kaliuretic peptide it is present in higher concentration in individuals with congestive heart failure. It causes the maximal increase in prostaglandin E2 (PGE2) levels of the three peptides. The known increase in PGE2 in chronic heart failure may be in part secondary to these peptides.