Electric field stimulation of cardiac myocytes during postnatal development

Studies on cardiac cell response to electric field stimulation are important for understanding basic phenomena underlying cardiac defibrillation, In this work, we used a model of a prolate spheroidal cell in a uniform external field (Klee and Plonsey, 1976) to predict the threshold electric field (E-T) for stimulation of isolated ventricular myocytes of rats at different ages. The model assumes that E-T is primarily determined by cell shape and dimensions, which markedly change during postnatal development, Neonatal cells showed very high E-T, which progressively decreased with maturation (experimental mean values were 29, 21, 13, and 5.9 and 6.3 V/cm for 3-6, 13-16, 20-21, 28-35, and 120-180 day-old rats, respectively, P V-T approximate to 35 mV, under our experimental conditions) was reasonably constant during development, except for cells from 1-mo-old animals, in which DeltaV(T) was lower than at other ages. We conclude that the model reasonably correlates E-T with cell geometry and size in most cases, Our results might be relevant for the development of efficient procedures for defibrillation of pediatric patients.48663063