Fig. 3.

Recovery of I_Na following its inhibition by exposure to apical HS (660 mosmol/kgH₂O). A: representative time course (n = 12) of the experimental protocol. After 17 min of exposure to the isosmotic solution (300 mosmol/kgH₂O), 10 μM amiloride was added to the apical bath. At 27 min of incubation, amiloride was removed. At 37 min of incubation, the apical solution was replaced by the HS solution (660 mosmol/kgH₂O). Once a steady value of I_SC was attained (i.e., at 56 min of incubation), amiloride was added at the apical side for a second time. At 63 min of incubation, amiloride was removed. When a steady value of I_SC was measured (i.e., at 75 min), the apical solution was replaced by the isosmotic solution. This manipulation produced a transient decrease in I_SC attributed to a reduction in the driving force for Na⁺ entry into the cell. After an allowance of 55 min of recovery (i.e., at 130 min of incubation), amiloride was added for a third and final time. The recovery of I_Na following reexposure to the isosmotic solution was calculated using Eq. 1. B: summary of 16 experiments (n = 4 at each recovery time measured) in which the %I_Na recovery following exposure to HS (660 mosmol/kgH₂O) was measured at various recovery times.