title: Ultrasound-induced modulation of cardiac rhythm in neonatal rat ventricular cardiomyocytes.
abstract: Isolated neonatal rat ventricular cardiomyocytes were used to study the influence of ultrasound on the chronotropic response in a tissue culture model. The beat frequency of the cells, varying from 40 to 90 beats/min, was measured based upon the translocation of the nuclear membrane captured by a high-speed camera. Ultrasound pulses (frequency = 2.5 MHz) were delivered at 300-ms intervals [3.33 Hz pulse repetition frequency (PRF)], in turn corresponding to 200 pulses/min. The intensity of acoustic energy and pulse duration were made variable, 0.02-0.87 W/cm(2) and 1-5 ms, respectively. In 57 of 99 trials, there was a noted average increase in beat frequency of 25% with 8-s exposures to ultrasonic pulses. Applied ultrasound energy with a spatial peak time average acoustic intensity (Ispta) of 0.02 W/cm(2) and pulse duration of 1 ms effectively increased the contraction rate of cardiomyocytes (P < 0.05). Of the acoustic power tested, the lowest level of acoustic intensity and shortest pulse duration proved most effective at increasing the electrophysiological responsiveness and beat frequency of cardiomyocytes. Determining the optimal conditions for delivery of ultrasound will be essential to developing new models for understanding mechanoelectrical coupling (MEC) and understanding novel nonelectrical pacing modalities for clinical applications.
authors: Department of Medicine, School of Medicine and.
authors: Andrew
authors: A
authors: Fleischman
authors: School of Biomedical Engineering, Science & Health System, Drexel University, Philadelphia, Pennsylvania; and.
authors: Christopher
authors: C
authors: Vecchio
authors: School of Biomedical Engineering, Science & Health System, Drexel University, Philadelphia, Pennsylvania; and.
authors: Youhan
authors: Y
authors: Sunny
authors: School of Biomedical Engineering, Science & Health System, Drexel University, Philadelphia, Pennsylvania; and.
authors: Christopher R
authors: CR
authors: Bawiec
authors: School of Biomedical Engineering, Science & Health System, Drexel University, Philadelphia, Pennsylvania; and.
authors: Peter A
authors: PA
authors: Lewin
authors: Department of Medicine, School of Medicine and School of Biomedical Engineering, Science & Health System, Drexel University, Philadelphia, Pennsylvania; and Department of Cardiothoracic Surgery, School of Medicine School of Medicine and Drexel University, Philadelphia, Pennsylvania.
authors: J Yasha
authors: JY
authors: Kresh
authors: Department of Medicine, School of Medicine and andrew.kohut@drexelmed.edu.
authors: Andrew R
authors: AR
authors: Kohut
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D002478:Cells, Cultured; D006339:Heart Rate / Q000528:radiation effects*; D040542:Mechanotransduction, Cellular / Q000528:radiation effects; D009200:Myocardial Contraction / Q000528:radiation effects*; D032383:Myocytes, Cardiac / Q000528:radiation effects*; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D000069453:Ultrasonic Waves
keywords: cardiomyocytes; electrophysiology; mechanoelectric coupling; mechanosensitivity; ultrasound modulation