Apparatus and methods are provided, including a bladder stimulator that includes an elongate element adapted to pass through a urethra or adapted to pass through another opening in the bladder, an expandable body coupled to said elongate element, and an array of one or more stimulator contacts coupled to the expandable body, the array including at least one contact adapted to contact a portion of a bladder of a subject when the expandable body is inserted in the bladder and expanded. A controller stimulates the portion of the bladder by driving a pulse into the bladder via the contact, the pulse having a frequency of 5 Hz-1 kHz. Other applications are also described.
