Steady-state approximations for Hodgkin-Huxley cell models: Reduction of order for uterine smooth muscle cell model
Fig 3
(Panel A) Disabling Ka current. FTM result with identical test protocol to the SSP reproduced by the CellML implementation (blue trace). Both [Ca2+]i and Vm (upper and lower Panes, respectively; note varying time scales) display similarity to FTM with Ka disabled and no modifications otherwise (black trace). Altered conductances for K1 and INa of 0.598 and 0.07 nS/pF, respectively, along with increased fraction of free (unbuffered) Ca2+ by 2.5% (β = 0.0154) presents improved qualitative fit to FTM (red trace, dotted). (Panel B) Disabling K2, Ka and h utilising the SSP as in Panel A. Disabling only K2 (black trace), exhibits significant rise in [Ca2+]i (upper pane), and truncated APs settling into elevated plateau Vm (lower pane) compared to FTM result (blue trace). Disabling K2, Ka and h shows similar behaviour (red trace). Alterations to K1 and INa of 0.655 and 0.05125 nS/pF, respectively, with β = 0.0146 improve qualitative fit to FTM (pilot-RTM, orange dotted). Experimental trace adapted from Tong, 2011 Fig 12A originally via Okabe, et al. [18] (inset, Panel B) showing pilot-RTM reproduces observed Vm peaks above 0 mV over 1 second. ‘Pilot-RTM’ here refers to interim reduced model; see text for more.