Abstract
Genetically engineered pacemaking in ventricular cells has been achieved by down-regulation of the time independent inward rectifying current (I K1), or insertion of the hyperpolarisation-activated funny current (I f). We analyse the membrane system (i.e. ionic concentrations clamped) of an epicardial Luo-Rudy dynamic cell model using continuation algorithms with the maximum conductance (\(\bar{g}\)) of I K1 and I f as bifurcation parameters. Pacemaker activity can be induced either via Hopf or homoclinic bifurcations. As \(\bar{g}\) K1 is decreased by ≈74%, autorhythmicity emerged via a homoclinic bifurcation, i.e., the periodicity first appear with infinitely large periods. In contrast, the insertion of \(\bar{g}\) f induced periodicity via a subcritical Hopf bifurcation at \(\bar{g}\) f≈ 0.25 mSμF−1. Stable autorhythmic action potentials occurred at \(\bar{g}\) f > 0.329 mSμF−1.
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Tong, W.C., Holden, A.V. Bifurcation Analysis of Genetically Engineered Pacemaking in Mammalian Heart. J Biol Phys 32, 169–172 (2006). https://doi.org/10.1007/s10867-006-9004-1
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DOI: https://doi.org/10.1007/s10867-006-9004-1