Fig. 9.

H₂S prevents increase in apical membrane ENaC activity by forskolin/IBMX. A: representative current traces of Ussing chamber experiments on basolaterally permeabilized H441 monolayers. The basolateral solution contained nystatin (1.5 × 10⁻⁴ M), ouabain (2 × 10⁻³ M), and high K⁺. After permeabilization, monolayers were incubated with forskolin/IBMX (fsk./IBMX), Na₂S (5 × 10⁻⁵ M), a combination thereof (Na₂S/fsk./IBMX), or no drugs at all (control), and the apical membrane was subsequently changed to a high Na⁺ solution (gray bar) to establish an apical to basolateral sodium gradient. Amiloride (ami.; 10⁻⁵ M) was applied afterward to determine amiloride-sensitive fractions (I_amiloride) of the apical membrane. B: statistical analysis of data shown in A. Depicted are apical membrane I_amiloride, which were normalized to the initial I_SC of intact monolayers before permeabilization (to compensate for alterations in baseline sodium transport capacity). Statistical analysis was performed by one-way ANOVA followed by Tukey's multiple-comparison test. ***P < 0.001. n = number within parentheses.