Effect of Bafilomycin A1 on the pH gradient across lamellar body membrane and surfactant secretion.

<p>(A) Overnight cultured cells were treated with 20 nM Bafilomycin A1 (Baf A1) for 1 hr. The quinacrine was added to a final concentration of 10 µM. Fluorescence microscopy was undertaken to monitor quinacrine staining. Shown are representative images from 3 independent cell preparations. Scale bar: 10 µm. (B) Freshly isolated type II cells were labeled with [³H]choline overnight. The cells were treated with 20 nM Baf A1 for 1 hr, followed by incubation with a combination of 100 µM ATP; 10 µM terbutaline and 0.1 µM PMA for 2 additional hrs. Surfactant secretion was expressed as a percentage of total cellular [³H] PC secreted into medium. Data shown are means ± SE (n = 12). *<i>P</i><0.05 <i>v.s.</i> Control (basal); ^#P<0.05 <i>v.s.</i> Baf A1 (basal); ^$P<0.05 <i>v.s.</i> Control (ATP+ Terbutaline +PMA) (ANOVA/Newman-Keuls Multiple Comparison Tests). <i>Open bars</i>, control; <i>shaded bars</i>, Baf A1.