A ventricular scar region was modelled by defining a circular region in the network within which each model ventricular cell was coupled to one model fibroblast by a conductance Gcf. The electrophysiological characteristics of heterologous gap junctions between cardiac fibroblasts and ventricular myocytes have so far been investigated in vitro only. The conductance of a single nexus connecting an individual cardiomyocyte to a single cardiac fibroblast in cell culture was found to be up to 4 nS at room temperature . Based on the assumption of intense electrotonic interaction of fibroblasts and cardiomyocytes in regions of fibroblast-rich growth in situ, Gcf was set in these simulations to 40 nS.
RESULTSElectrotonic interactions between fibroblasts and SA node cells: The ways in which opening of Gstretch(t) in fibroblasts affects oscillation properties of the main cardiac pacemaker were examined in a model SA node embedded within a grid of model atrial cells, as described above. For the initial simulations, a coupling conductance between SA node cells and fibroblasts of Gcf = 600 pS was selected. The whole network was allowed to pace for seven beats without activation of Gstretch(t) in the fibroblasts. The purpose of this was to allow the SA node cells to approach a steady-state pattern of oscillation, so that the background spontaneous depolarization rate could be determined. On repolarization after the seventh beat, the Gstretch(t) in the fibroblasts was turned on at negative threshold crossing (-30 mV) in the reference cell. It’s time to pay less money – just get sale viagra online at the best online pharmacy.