Ultrasound-induced modulation of cardiac rhythm in neonatal rat ventricular cardiomyocytes

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 hi...

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Bibliographic Details
Published in:Journal of applied physiology (1985) 2015-06, Vol.118 (11), p.1423-1428
Main Authors: Fleischman, Andrew, Vecchio, Christopher, Sunny, Youhan, Bawiec, Christopher R, Lewin, Peter A, Kresh, J Yasha, Kohut, Andrew R
Format: Article
Language:English
Subjects:
Acoustics
Animals
Animals, Newborn
Cardiac Pacing, Artificial - methods
Cardiomyocytes
Cells, Cultured
Frequencies
Heart rate
Heart Rate - radiation effects
Mechanotransduction, Cellular - radiation effects
Myocardial Contraction - radiation effects
Myocytes, Cardiac - radiation effects
Physiology
Rats, Sprague-Dawley
Rodents
Time Factors
Ultrasonic imaging
Ultrasonic Waves
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Summary: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.
ISSN:8750-7587
1522-1601
DOI:10.1152/japplphysiol.00980.2014