For example, while 2A-containing receptors exhibit greater open channel probability in heterologous systems, measuring the progression of activity-dependent channel block does not support the same conclusion in neurons but rather data in neurons show evidence for similar open probability kinetics (Wang et al., 2011; Speed and Dobrunz, 2009; Chavis and Westbrook, 2001).
This fractional activation value is slightly greater than the open probability values plotted in Figure 1D, for which the mean was 0.7 ± 0.1 (N = 5).
Because G190S induced a great positive shift of ClC-1 open probability, we wondered whether ACTZ may be able to counteract the effect of the mutation.
Rat, but not human, T-tubule LTCCs had open probability similar to crest LTCCs, but exhibited ≈40% greater current.
This phosphorylation increases the open probability of the channel [ 19], allowing for greater trans-sarcolemmal Ca2+ influx with each depolarization and producing, in part, the positive inotropic effect of epinephrine.
This phosphorylation increases the open probability of the channel [ 10], allowing for greater trans-sarcolemmal Ca2+ influx with each depolarization and producing, in part, the positive inotropic effect of Epi.
It has been proposed that RyR3 may be preferentially targeted to the SR within these junctions because, compared with RyR1 and RyR2, RyR3 exhibits a relatively high EC50 for CICR, a marked Ca2+-dependent increase in gain (open probability, Po + mean open time) and a greater resistance to inactivation by high (mM) [Ca2+] (for detailed discussion see Ref. 48).
We note that while conductance assays require higher open probability for detection, dye permeability experiments are more sensitive and can detect even a small probability of opening.
Considering the lower open probability (∼0.3 under these recording conditions) and smaller single channel conductance of Slo3 channels compared to Slo1 channels [22], [25], the actual membrane density of Slo3 channels is expected to be greater than that of Slo1 channels.
