Significance of muscle hyperthermia during sonoporation

Abstract

Ultrasound induced heating of muscle was monitored during muscle sonoporation. Generation of heat started simultaneously after the increase of ultrasound intensity and ultrasound exposure duration above the threshold values. On the contrary, the decrease of ultrasound duty cycle to 20% and frequency to 1 MHz helped to maintain the muscle temperature unchanged within 4 min of ultrasound application. The delivery of ultrasound via 24 mm transducer induced the higher temperature of muscle in comparison to 6 mm. Alongside the direction of ultrasound beam propagation (from the surface into the depth of the muscle) the temperature in situ decreased exponentially. We conclude that ultrasound induced thermal damage of tissue might interfere with sonoporation bioeffects via mechanism reducing the efficiency of reversible sonoporation and increasing the efficiency of irreversible sonoporation.