Use of ultrasound to control ion transport via changes in membrane bound ATPase activity

Ultrasound frequencies ranging from 26 kHz to 10 MHz are used in a number of applications varying from cell disruptions to therapeutic and diagnostic procedures. Previous results demonstrated that 1 MHz ultrasound at therapeutic intensities causes significant changes in the electrophysiological properties of epithelial tissues. The nature of these alterations indicated that, among other effects, the Na/K-dependent ATPase activity of the tissue was reduced. This study examined if ultrasonic irradiation does effect ATPase activity. Two model systems were studied, a "free" solution of ATPase and a membrane-incorporated Na/K-dependent ATPase. The experiments indicated an irreversible decreased in enzyme activity for both systems and that sono-chemical (e.g., free radicals) and not thermal effects are responsible. These results support the authors' hypothesis from previous electrophysiological observations on frog skin preparations that the effects of ultrasonic irradiation were, in part, due to effects on the activity of Na/K-dependent ATPase. Furthermore, the results of this study demonstrate that sono-chemical-induced enzyme activity changes may represent a much more common and pervasive effect than is commonly realized.