Modeling K+ channels for a ventricular cell model

The recent experimental data demonstrated the significance of the cardiac K⁺ currents in the rat ventricular myocytes under different pathological (normal, diabetic, altered thyroid, and hypertrophied) conditions. A computer model of the rat ventricular cell is being developed from both voltage clamp and action potential data to determine the contribution of the outward K⁺ currents to the action potential variation in normal and diseased rat ventricular myocytes. The ventricular cell model has two major components: a Hodgkin-Huxley type membrane model and a fluid compartment model. The membrane model of the ventricular cell is described by the membrane capacitance, the ionic currents, and the membrane pumps and exchanger. The main objective of this study was to develop mathematical equations to model the two prominent K⁺ channels (I_t and I _K1). The results conclude that (i) the voltage and time dependencies of the 4AP sensitive transient outward current (I_t ) can be represented by the Hodgkin-Huxley type descriptions, (ii) the voltage and K₀⁺ dependencies of the instantaneous rectifier current (I_K1) can be formulated by a simple nonlinear equation, and (iii) the voltage clamp simulations for I _t and I_K1 match the experimental data well