Dependences of the geometrical parameters of cell community on stimulation voltage and frequency in chick embryonic cardiomyocytes

• Published in: Japanese Journal of Applied Physics Vol. 57; no. 3S2; pp. 3 - 8
• Main Authors: Fujii, Koki, Nomura, Fumimasa, Kaneko, Tomoyuki
• Format: Journal Article
• Language: English
• Published: Tokyo The Japan Society of Applied Physics 01.03.2018; Japanese Journal of Applied Physics
• Subjects: Cardiomyocytes; Communities; Dependence; Fibrillation; Fibroblasts; Heart; Orientation; Stimulation; Threshold voltage; Ventricular fibrillation
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.57.03EB04

To investigate the optimal conditions for electrical stimulation, communities of lined-up chick embryonic cardiomyocytes were evaluated in terms of their threshold voltage for pacing (PVMin) and the half-maximum paced frequency (PF50), with a focus on the following factors: (1) the orientation of the major axis of cell communities to the electric field (EF) direction as the external factor; (2) the number of cells in a cell community, the length of the cell community, and the mean length of cells comprising the community as the internal factors. Firstly, PVMin decreased with increasing length of the cell network oriented parallel to the EF. PVMin was approximately 0.041 ± 0.025 V/mm when the community was sufficiently long. On the other hand, PVMin in the orthogonal orientation was constant at 1.7 ± 0.047 V/mm with no dependence on the length of the cell network. Secondly, we found that PF50 increased with increasing length of the cell network or the number of cells in the network; the PF50 values were 2.03 ± 0.05 and 3.39 ± 0.05 Hz when the respective cell network lengths were 100 µm (n = 43) and more than 300 µm (n = 6) and the cells were oriented parallel to the EF. These findings indicate that it is important to suppress ventricular fibrillation with minimal efficient stimulation by considering the EF direction with respect to the orientation of cardiomyocytes. Furthermore, expanded cells showed the loss of ability to respond to stimulation at higher frequencies. Cardiomyocytes combined with seeded fibroblasts as a cell network at a low density are a possible model of a ventricular remodeling heart.