Systems and methods treat a tissue region at or near a sphincter by deploying a carrier, which carries an electrode that can be advanced to penetrate tissue. Negative pressure is applied through a suction port on the carrier near the electrode, to draw tissue in the tissue region inward against the carrier. The systems and methods advance the electrode to penetrate tissue drawn against the carrier. The vacuum anchors the surrounding tissue and mediates against the “tenting” of tissue during electrode penetration. Without tenting, the electrode penetrates mucosal tissue fully, to obtain a desired depth of penetration.