Meeting Abstract
The transmembrane voltage and intracellular calcium dynamics in cardiac muscle varies greatly across species. Through the use of high spatiotemporal resolution optical mapping on Langendorff perfused hearts, we’ve analyzed the voltage and calcium dynamics in zebrafish, frogs, rabbits, rats, cats, dogs, pigs, ferrets, and alligators. I will focus my discussion on alternans, a pro-arrhythmic period doubling bifurcation in cardiac action potentials resulting from increasing rate of stimulation. Understanding the mechanisms underlying alternans is of great importance, as this dynamical instability provides an arrhythmic substrate for fibrillation and is strongly correlated with sudden cardiac death. In zebrafish hearts the onset of alternans is driven by the voltage dynamics in a pitchfork bifurcation, whereas alternans in rabbits and cats is driven by calcium dynamics in a border collision bifurcation, but although rabbits display voltage alternans, cats do not. Pigs and alligators do not develop alternans in either voltage or calcium, but alligators do not fibrillate. In this talk I will discuss more species and how the mechanisms underlying alternans can vary.
