Fig. 4.
Mutation of the local anesthetic receptor residue (F1760A) reduces UDB of peak sodium channel current by propranolol. (A) Shown are averaged peak Na+ recordings F1760 channels in the presence and absence (inset) of 40 μM propranolol. Currents are normalized to the peak current in control conditions. (B) UDB at a fixed pulse frequency (5 over a range of propranolol concentrations (40 nM to 400 μM). Again the curves are the best fits of the Hill equation (see previous) to the data. The estimated IC50 and n obtained from the fit are 172.7 μM and 3.4 (n=4–5 cells).