Apparatus for treating a body of a subject is provided. The apparatus includes (1) a first electrode, configured to be placed at a first site in the body of the subject, (2) a second electrode, configured to be placed at a second site in the body of the subject, (3) a pressure sensor, configured to detect a pressure at at least the first site, and (4) a control unit, configured to, at least in part responsively to the detected pressure, induce electroosmotic movement of a fluid between the first and second sites, by driving a current between the first and second electrodes. Other embodiments are also described.
