AGONISTS OF GUANYLATE CYCLASE AND THEIR USES

1 - 16 . (canceled)

17 . A method of colonic cleansing, comprising administering to a subject in need thereof a liquid osmotic colonic evacuant and a unit dose of 0.01 mg to 60 mg of a guanylate cyclase receptor agonist (GCRA) peptide consisting essentially of the sequence of SEQ ID NO: 1 or SEQ ID NO: 9.

18 . The method of claim 17 , wherein said osmotic colonic evacuant is magnesium citrate.

19 . The method of claim 17 , wherein said osmotic colonic evacuant comprises a phosphate salt laxative.

20 . The method of claim 17 , wherein said osmotic colonic evacuant comprises a sulfate salt laxative.

21 . The method of claim 19 , wherein the phosphate salt is chosen from sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium biphosphate, sodium acid pyrophosphate, or any combination thereof.

22 . The method of claim 20 , wherein the sulfate salt is chosen from sodium sulfate, potassium sulfate, magnesium sulfate, or any combination thereof.

23 . The method of claim 17 , the method further comprising administering to said subject an effective amount of at least one of L-glucose, lubiprostone, prucalopride, an agent for treating chronic constipation, or any combination thereof.

24 . The method of claim 23 , wherein the effective amount of L-glucose is a unit dose of 20 g-200 g.

25 . The method of claim 17 , the method further comprising administering to said subject an effective amount of a cGMP-specific phosphodiesterase inhibitor.

26 . The method of claim 25 , wherein said cGMP-specific phosphodiesterase inhibitor is chosen from sulindac sulfone, zaprinast, motapizone, vardenafil, and sildenafil, or any combination thereof.