Reabsorption of lung liquid produced by 2,4-dinitrophenol in in vitro lungs from fetal guinea pigs

Abstract

Lungs from near-term fetal guinea pigs (62 ± 2 days of gestation) were supported in vitro for 3 h, and lung liquid production was measured by a dye dilution technique. Twelve untreated preparations produced fluid at 1.54 ± 0.29 mL∙kg−1 body weight∙h−1 during the 1st h, with no significant changes in later hours. Twelve preparations treated with 2 × 10−4 M 2,4-dinitrophenol (DNP) showed strong reabsorptions (significant, ANOVA and regression analysis); total loss of lactate from the preparations doubled (significant, same tests). In 12 additional preparations, increasing DNP fivefold did not abolish reabsorption; results resembled those at the lower concentration. Amiloride at 10−6 M abolished reabsorptions after 2 × 10−4 M DNP, although fluid production still halted (n = 6; reductions significant, same tests). Amiloride alone had no effect (n = 6); untreated controls showed no change (n = 6). Similarly, 10−4 M sodium iodoacetate virtually abolished reabsorptions after 2 × 10−4 M DNP, although fluid production still stopped (n = 6; reductions significant, same tests). Iodoacetate alone only reduced fluid production (n = 6; significant, same tests); untreated controls showed no change (n = 6). The results suggest that reabsorptions seen after inhibition of oxidative processes depend on amiloride-sensitive Na+ channels and glycolytic metabolism.Key words: fetus, lung liquid, 2,4-dinitrophenol, amiloride, iodoacetate.