The cDNA sequence encoding porcine brain natriuretic peptide and related genes encoding canine and human peptides with natriuretic activity are disclosed. The gene is shown to make accessible the DNAs encoding analogous natriuretic peptides in other vertebrate species. The genes encoding these NPs can be used to effect modifications of the sequence to produce alternate forms of the NPs and to provide practical amounts of these proteins. The NPs of the invention can also be synthesized chemically. The invention peptides have the formula: R1-Cys-Phe-Gly-Arg- Arg/ - Leu/ -Asp-Arg-                     Lys    Met                                                (1)    Ile- Gly/ -Ser- Leu/ -Ser-Gly-Leu-Gly-Cys-R-2         Ser        Ser wherein R1 is selected from the group consisting of:                                              (H);                                             Gly-;                                         Ser-Gly-;                                   Asp/                                   Lys/ -Ser-Gly-;                                   Gly                            Arg/   Asp/                            His/ - Lys/ -Ser-Gly-;                            Gln    Gly                            Arg/   Asp/                     Met/ - His/ - Lys/ -Ser-Gly-;                     Val    Gln    Gly                            Arg/   Asp/              Thr/ - Met/ - His/ - Lys/ -Ser-Gly-;              Met    Val    Gln    Gly                            Arg/   Asp/         Lys- Thr/ - Met/ - His/ - Lys/ -Ser-Gly-;              Met    Val    Gln    Gly                            Arg/   Asp/     Pro-Lys- Thr/ - Met/ - His/ - Lys/ -Ser-Gly-;              Met    Val    Gln    Gly                            Arg/   Asp/ Ser-Pro-Lys- Thr/ - Met/ - His/ - Lys/ -Ser-Gly-;              Met    Val    Gln    Gly or a 10- to 109-amino acid sequence shown as the native upstream sequence for porcine, canine or human BNP in FIG. 8, or a composite thereof; R2 is (OH), NH2, or NR′R″ wherein R′ and R″ are independently lower alkyl (1-4C) or is Asn/ Lys Asn/ -Val Lys Asn/ -Val-Leu Lys Asn/ -Val-Leu-Arg Lys Asn/ -Val-Leu-Arg- Arg/ Lys                Lys Asn/ -Val-Leu-Arg- Arg/ - Tyr/ Lys                Lys    His or the amides (NH2 or NR′R″) thereof, with the proviso that if formula (1) is R1-Cys-Phe-Gly-Arg-Arg-Leu-Asp-Arg-    Ile-Gly-Ser-Leu-Ser-Gly-Leu-Gly-Cys-R2 and R1 is Asp-Ser-Gly-, R2 cannot be Asn-Val-Leu-Arg-Arg-Tyr. The peptides of the invention can be formulated into pharmaceutical compositions and used to treat conditions associated with high extracellular fluid levels, especially congestive heart failure.