Apparatus is provided, including an implantable mechanical support, shaped to support a portion of a urethra of a patient. One or more electrodes are coupled to the mechanical support, so as to contact tissue of the patient when the mechanical support is implanted in the patient. A control unit drives the electrodes to apply a current to the tissue. A method for treating a patient is also provided, including implanting a mechanical support in a position that supports a urethra of a patient. In response to increased pelvic pressure of the patient, a substance stored in a portion of the mechanical support that is not under the urethra is moved to a portion of the mechanical support that is under the urethra. Other embodiments are also described.