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. Author manuscript; available in PMC: 2010 Jul 17.
Published in final edited form as: Channels (Austin). 2009 Jul 17;3(4):249–258. doi: 10.4161/chan.3.4.9253

Figure 4.

Figure 4

GV curves simulated by the HA model with changes in the value of the coupling factor C for the Ca2+ bowl-defective Slo1 channel. A. Simulated GV curves for the conditions with no Ca2+ (thin curve) and with 200 μM Ca2+ (thick curve). The value of C, 2.6 ± 0.09, was estimated based on the Po measurements at −120 mV. The line width of the GV curves represents SEM. B. GV results at different pHi fit with the HA model (smooth curves) with C = 2.14 and KD = 1.31 μM. The measured results are from Avdonin et al.25 C. The V0.5-pHi relation from B is compared with the prediction of the model. The model accounts for an approximate − 50 mV GV shift from pH 7.5 to 6.2 while also predicting a 3.97-fold increase in Po at −120 mV, similar to the observed 3.14-fold increase. Most of the other parameters in the model were fixed to values previously determined by Horrigan et al (zJ = 0.55 e0, zL = 0.38 e0, D =11.6, E = 2.4), while L0 = 7.1 × 10−6 and Vh(J) = 94 mV were allowed to vary freely.