Single SA node cell models were derived from the formulation of Noble et al . These models, based on experimental data from the rabbit, were adjusted to account for differences in SA node cell oscillation properties with increasing distance from the SA node centre . The complete dynamic equations describing these modifications are presented elsewhere . Briefly, differences between action potentials of peripheral versus central SA node cells were modelled by increasing linearly with increasing distance from the node centre the magnitude of INa (maximum fast + 2+ inward Na current), Isi,Ca (slow inward Ca current), If (hyperpolarization-activated inward current) and IK (time-dependent K+ current). This accounts for larger upstroke velocity, larger overshoot potentials, larger oscillation frequency and greater sensitivity to changes in external K+ concentration seen in cells isolated from peripheral versus central regions of the node .
Since the SA node contains a very large population of connective tissue cells , electrical models of fibroblasts were included within the SA node. The fibroblast model used has been described previously . Briefly, each fibroblast is modelled as a membrane capacitance (100 pF) in parallel with a resting membrane conductance (usually 1 nS) and a variable, stretch-activated conductance (Gstretch(t)). The resting membrane conductance is in series with a battery setting the resting membrane potential to -20 mV, as observed in vitro and in situ . Gstretch(t) is in series with a battery setting the reversal potential of the stretch-activated current to 0 mV, as seen in fibroblasts in vitro. Take advantage of this chance to find viagra super active online and save quite some money.
Computational study of the impact of cardiac mechanosensitive fibroblasts on heart rhythm (part 4)
This entry was posted in Cardiology and tagged Cardiac connective tissue, Computer model, Mechano-electric feedback, Scar tissue, Sinoatrial node, Ventricle.