Figure 6:

Sequential ASL volume responses to aerosolized 7% HS for 15 min (8μg NaCl/cm²/min). (A) Sequential ASL volume responses to aerosolized HS. A smaller ASL response to a second administration of aerosolized HS was observed when two identical HS doses were separated by 15 minutes. Break in x-axis indicate time between two doses. For each dose, HS was nebulized at 8 μg NaCl/cm²/min, administered continuously for 15 minutes. The ASL height of the second peak was about 60% of the first peak. (B) A hypotonic saline rinse was interposed between HS administration. The hypotonic solution administration produced cellular swelling associated with improved ASL volume responses to a subsequent administration of HS (~140% of first dose). (C) Interposition of an isotonic rinse between the first and second HS administration. The same second dose effect is not seen when doses of HS were separated by an isotonic saline bolus. ASL height of second peak persisted ~50% of the first peak. (D) In model simulation, the water permeability of the HBE apical membrane during the second dose was reduced to 10% of the basal water permeability. N=4 for each condition.