The present disclosure is directed to compounds of the structure (X): CoreL-NHE)n  (X) wherein: n is 2 or 3; NHE has the structure wherein: R1 is H or —SO2—NR7R8—; R2 is selected from H, —NR7(CO)R8, —SO2—NR7R8— and —NR7R8; R3 is hydrogen; R7 is hydrogen; R8 is a bond linking to L; L is a polyalkylene glycol linker; and Core has the following structure: wherein: X is selected from the group consisting of a bond, —O—, —NH—, NHC(═O)—, —NHC(═O)NH— and —NHSO2—; and Y is selected from the group consisting of a bond, optionally substituted C1-6 alkylene, optionally substituted benzene, pyridinyl, a polyethylene glycol linker and —(CH2)1-6O(CH2)1-6—, and methods of using such compounds for the treatment of irritable bowel syndrome, chronic kidney disease and end-stage renal disease.