Fig. 4.

The Cat-S inhibitor LHVS has no effect on ENaC activation by the serine proteases trypsin and chymotrypsin. a Oocytes expressing human ENaC were incubated for 30 min in protease-free solution (control), in solutions with different concentrations of chymotrypsin (0.02, 0.2, and 2 μg/ml), in LHVS (2 μM), or in solutions containing a combination of different concentrations of chymotrypsin (0.02, 0.2, and 2 μg/ml) and LHVS (2 μM). Amiloride-sensitive whole-cell currents (ΔI _ami) were determined before (−) and after (+) incubation. Columns represent relative stimulatory effect on ΔI _ami calculated as the ratio of ΔI _ami measured after 30 min of incubation (ΔI _ami 30 min) to the initial ΔI _ami (ΔI _ami initial) measured before incubation. Numbers inside the columns indicate the number of individual oocytes measured. b Similar experiment as shown in a using the serine protease trypsin (2 μg/ml) instead of chymotrypsin