Ventricular network modelling: Individual ventricular cells were modelled using the formulations of Noble et al based on data from the guinea-pig. Ventricular networks were modelled using two-dimensional cell lattices in which each interior cell of the lattice was coupled resistively to its four nearest neighbours. The coupling conductance between cardiomyocytes, Gcc, equalled 1 |J,S and was uniform throughout the network.
Cardiac mechanosensitive fibroblasts were modelled as described in the previous section. Diastolic stretch of the fibroblasts was simulated by a transient increase in total membrane conductance from the resting level (here 2 nS) to 100 nS. These values conform with changes observed in experiments on cardiac mechanosensitive fibroblasts where the total membrane resistance declined from levels around 10Q under control conditions to values in the order of 10Q under stretch . In these simulations the stretch-dependent membrane conductance, Gstretch(t), was activated in a trapezoidal fashion (ramp-on and ramp-off times 20 ms, total duration 80 ms).
Ventricular network dynamic equations were integrated using the massively parallel CM-5 supercomputer of Thinking Machines Inc (Cambridge, Massachusetts, USA). Implementation of two-dimensional cardiac cell network models on the CM-5 systems have been described previously . The numerical integration algorithm used was a fourth order, adaptive step Runge-Kutta algorithm. Visit the best pharmacy giving you sale cialis tablets and taking the best care of you.