The effect of therapeutic ultrasound on electrophysiological parameters of frog skin

• Published in: Ultrasound in medicine & biology Vol. 15; no. 5; pp. 461 - 470
• Main Authors: Dinno, Mumtaz A., Crum, Lawrence A., Wu, Jisen
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 1989; Elsevier
• Subjects: Acoustic cavitation; Animals; Biological and medical sciences; Biological Transport; Conductance; Continuous wave; Effects of various physical factors on living matter (vibrations, electric field, ultrasound, sound...); Electrophysiology; Epithelial membranes; Frog skin; Fundamental and applied biological sciences. Psychology; Intensity; Ion transport; Ions - physiology; Membrane potential; Membrane Potentials; Nonthermal effects; Pulsed wave; Rana pipiens; Short circuit current; Skin Physiological Phenomena; Sodium transport; Therapeutic ultrasound; Thermal effects; Tissues, organs and organisms biophysics; Ultrasonic Therapy; Short circuit current; Intensity; Therapeutic ultrasound; Ion transport; Acoustic cavitation; Pulsed wave; Nonthermal effects; Sodium transport; Continuous wave; Frog skin; Thermal effects; Epithelial membranes; Conductance; Membrane potential; Temperature; Ultrasonic investigation; Carbon dioxide; Ionic conductivity; Electrophysiology; Models; Skin; Ultrasound; Biological system
• ISSN: 0301-5629; 1879-291X
• DOI: 10.1016/0301-5629(89)90099-9

There are two groups of mechanisms through which ultrasound can affect biological systems, those of thermal origin and others of nonthermal origin. Since in almost every therapeutic application of ultrasound, movement of ions across cellular membranes is involved, it becomes important to study the effect of ultrasound on active and passive ionic conductance. In order to differentiate between thermal and nonthermal effects, a study was conducted on model systems in which the effect of temperature is known. The well-known sodium transporting epithelium, the epidermis of abdominal frog skin, was investigated and the effect of therapeutic ultrasound on its electrophysiological properties was determined. It was found that under open circuit conditions, irradiation of the skin with 1 MHz cw (60–480 mW/cm 2) ultrasound caused a significant decrease (5–50%, depending on the applied power) in the transepithelial potential and resistance at room temperature (20–22°C). Under short circuit conditions, also at room temperature, there was an increase in total ionic conductance (20–250%, depending on the applied power) and a decrease in the net actively transported current, measured as the short circuit current. These effects are reversible within the range of powers used. Furthermore, it was found that the magnitude of the observed changes was strongly dependent on the perfusion rate and the gas content of the bathing medium. The effect of ultrasound diminished in the presence of CO 2 and was enhanced with faster perfusion rates. Pulsed ultrasound delivered at the same energy ( I sata) as that of cw caused a significantly larger effect. At lower temperatures (12–14°C) the effect of ultrasound was reduced. Analysis of the data reveals that the effects of ultrasound on ion transport reported here are not primarily of thermal origin but are probably due to cavitation and related effects, such as microsteaming.