“…It is reported that cell lysis induced by ultrasound results from disruption of the cell membrane due to mechanical shearing stress arising from cavitation (Hughes and Nyborg 1962) . Procaine, a local anaesthetic acting on the membrane, has been shown to enhance the response to hyperthermia (Yau 1979) andultrasound (Ben-Hur andGreen 1982) . Procaine, a local anaesthetic acting on the membrane, has been shown to enhance the response to hyperthermia (Yau 1979) andultrasound (Ben-Hur andGreen 1982) .…”