class="enumerated" style="list-style-type:decimal">Isolated rat fetal distal lung epithelial (FDLE) cells were cultured (for 48 h) at PO2 levels between 23 and 142 mmHg. Higher PO2 levels between 23 and 142 mmHg. Higher PO2 was associated with increased short circuit current (ISC) and increased abundance of the Na+ channel protein α-ENaC. PO2 had no effect upon ISC remaining after apical application of amiloride (10 μM).Studies of cells maintained (for 48 h) at PO2 levels of 23 mmHg or 100 mmHg, and subsequently nystatin permeabilized (50 μM), showed that high PO2 increased Na+ pump capacity. This response was apparent 24 h after PO2 was raised whilst it took 48 h for the rise in ISC seen in intact cells to become fully established. Both parameters were unaffected by raising PO2 for only 30 min.Basolateral application of isoprenaline (10 μM) did not affect ISC in cells maintained at 23 mmHg but evoked progressively larger responses at higher PO2. The response seen at 142 mmHg was larger than at 100 mmHg, the normal physiological alveolar PO2.Isoprenaline had no effect on Na+ pump capacity at PO2 levels of 23 mmHg or 100 mmHg, but stimulated Na+ extrusion at 142 mmHg. Increasing PO2 above normal physiological levels thus allows the Na+ pump to be controlled by isoprenaline. This may explain the enhanced sensitivity to isoprenaline seen under these slightly hyperoxic conditions.Changes in PO2 mimicking those occurring at birth thus exert profound influence over Na+ transport in FDLE cells and the Na+ pump could be an important locus at which this control is exercised.
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机译:class =“ enumerated” style =“ list-style-type:decimal”> <!-list-behavior =枚举前缀-word = mark-type = decimal max-label-size = 0-> 在23至142 mmHg之间的PO2水平下培养分离的大鼠胎儿远端肺上皮(FDLE)细胞(持续48小时)。 PO 2含量在23至142 mmHg之间。较高的PO2与短路电流(ISC)的增加和Na + sup>通道蛋白α-ENaC的丰度增加有关。顶端应用阿米洛利(10μM)后,PO2对残留的ISC没有影响。 li> 对PO2浓度维持在23 mmHg或100 mmHg的细胞研究(持续48小时),随后制霉菌素通透性(50μM)的研究),表明高PO2可以增加Na + sup>泵的容量。 PO 2升高后24小时,这种反应是明显的,而完整细胞中I SC sub>的升高需要48小时才能完全确立。升高P O 2 sub> sub>仅30分钟都不会影响这两个参数。 li> 异丙肾上腺素(10μM)的基底外侧应用对I 不产生影响细胞中的SC sub>保持在23 mmHg,但在P O 2 sub> sub>较高时引起更大的反应。 142 mmHg的反应大于100 mmHg的反应,正常的生理性肺泡P O 2 sub> sub>。 li> 异丙肾上腺素对Na O 2 sub> sub>浓度为23 mmHg或100 mmHg时 sup>泵容量,但在142 mmHg时刺激Na + sup>挤出。因此,将P O 2 sub> sub>增加到正常生理水平以上,就可以使Na + sup>泵受异丙肾上腺素的控制。这可能解释了在这些轻微高氧条件下对异丙肾上腺素的敏感性增强。 li> P em> O 2 sub> sub> sub>的变化类似于那些因此,在出生时发生这种情况会对FDLE细胞中的Na + sup>转运产生深远的影响,而Na + sup>泵可能是行使这种控制的重要场所。 li> < / ol>
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