Q. An 8-year-old boy is brought to the pediatrician's office by his mother, who reports that he has been wetting the bed almost every night for the past year. The child is otherwise healthy and has no significant medical history. The pediatrician diagnoses the child with primary nocturnal enuresis and prescribes Desmopressin. The child's mother is interested in understanding how the medication works to stop bedwetting. What is the mechanism of action of desmopressin in the treatment of primary nocturnal enuresis?