Ariful Islam and Abhishek Murthy Stony Brook University Title: Bisimulation-Based Abstraction of Sodium-Channel Dynamics in Cardiac-Cell Models Radu Grosu, Flavio H. Fenton, Ariful Islam, Abhishek Murthy, Scott A. Smolka Abstract: We describe work in progress on deriving an abstract 4-variable cardiac-cell model from a very detailed 67-variable model using a formal abstraction pathway based on approximate bisimulation between continuous systems. Our current focus is on the sodium-channel dynamics during the upstroke phase of a cardiac cell's action potential.