Sheep lungs were artificially perfused in situ with warmed whole oxygenated sheep blood. The airspaces of the lungs were filled with liquid containing an impermeant tracer, to allow measurement of the rate of net transepithelial liquid movement under various conditions. 2. Dichlorobenzamil (1.5 x 10-5 M), a blocker of cyclic nucleotide-gated cation channels, inhibited the resting absorption of lung liquid in sheep aged 6 months (n = 5) (from -36.47 +/- 4.62 to -4.36 +/- 5.27 ml h-1, means +/- s.e.m.; P < 0.005, paired t test). Amiloride (10-4 M), a blocker of epithelial sodium channels, had no additive effect to that of dichlorobenzamil. 3. In the lungs of sheep aged 6 months (n = 4), amiloride (10-4 M) partially inhibited the resting absorption of liquid (from -35.21 +/- 8.57 to -11.05 +/- 4.91 ml h-1; P < 0.05, one-tailed paired t test), and dichlorobenzamil (1.5 x 10-5 M) exerted an additive effect to that of amiloride resulting in secretion at +6.29 +/- 3.05 ml h-1 (P < 0. 01, paired t test). 4. In the lungs of sheep aged 6 weeks (n = 3), amiloride (10-4 M) also inhibited the resting absorption of liquid (from -26.36 +/- 14.05 to -5.17 +/- 8.27 ml h-1; P < 0.05, one-tailed paired t test); however, dichlorobenzamil (1.5 x 10-5 M) did not exert an additive effect to that of amiloride. 5. In the lungs of sheep aged 6 months (n = 4), amiloride (10-4 M) partially inhibited the resting absorption of liquid (from -35.70 +/- 8.58 to -6.79 +/- 4.28 ml h-1; P < 0.05, paired t test), and pimozide (1.5 x 10-4 M), another blocker of cyclic nucleotide-gated cation channels, also exerted an additive effect to that of amiloride, resulting in secretion of lung liquid at +15.36 +/- 9.14 ml h-1 (P < 0.05, paired t test). 6. We conclude that cyclic nucleotide-gated cation channels mediate a component of lung liquid absorption in sheep aged 6 months (but not in sheep aged 6 weeks), and that a mechanism for lung liquid secretion (present in fetuses) is retained at 6 months of age.
摘要
对绵羊的肺进行原位人工灌注温热的全氧合绵羊血液。肺的气腔充满含有不透性示踪剂的液体，以测量在各种条件下净跨上皮液体移动的速率。2. 二氯苯甲酰胺（1.5×10⁻⁵ M），一种环核苷酸门控阳离子通道阻滞剂，抑制6月龄绵羊（n = 5）肺液的静息吸收（从-36.47±4.62降至-4.36±5.27 ml h⁻¹，均值±标准误；P < 0.005，配对t检验）。氨氯吡脒（10⁻⁴ M），一种上皮钠通道阻滞剂，对二氯苯甲酰胺无附加作用。3. 在6月龄绵羊（n = 4）的肺中，氨氯吡脒（10⁻⁴ M）部分抑制液体的静息吸收（从-35.21±8.57降至-11.05±4.91 ml h⁻¹；P < 0.05，单尾配对t检验），二氯苯甲酰胺（1.5×10⁻⁵ M）对氨氯吡脒有附加作用，导致液体分泌为+6.29±3.05 ml h⁻¹（P < 0.01，配对t检验）。4. 在6周龄绵羊（n = 3）的肺中，氨氯吡脒（10⁻⁴ M）也抑制液体的静息吸收（从-26.36±14.05降至-5.17±8.27 ml h⁻¹；P < 0.05，单尾配对t检验）；然而，二氯苯甲酰胺（1.5×10⁻⁵ M）对氨氯吡脒无附加作用。5. 在6月龄绵羊（n = 4）的肺中，氨氯吡脒（10⁻⁴ M）部分抑制液体的静息吸收（从-35.70±8.58降至-6.79±4.28 ml h⁻¹；P < 0.05，配对t检验），匹莫齐特（1.5×10⁻⁴ M），另一种环核苷酸门控阳离子通道阻滞剂，对氨氯吡脒也有附加作用，导致肺液分泌为+15.36±9.14 ml h⁻¹（P < 0.05，配对t检验）。6. 我们得出结论，环核苷酸门控阳离子通道介导6月龄绵羊（但不是6周龄绵羊）肺液吸收的一部分，并且胎儿期存在的肺液分泌机制在6月龄时保留。
