Iino Y, Burg M B
Jpn J Physiol. 1981;31(1):99-107. doi: 10.2170/jjphysiol.31.99.
In previous studies, when rabbit cortical collecting ducts were studied under standard conditions in vitro, bicarbonate transport was conditioned by the acid-base status in vivo of the animals from which the tubules were obtained. The collecting ducts absorbed bicarbonate if the animals were acidotic (from ammonium chloride administration), but they secreted bicarbonate if the animals were alkalotic (from sodium bicarbonate administration). The purpose of the present studies was to test whether similar conditioning occurs in other nephron segments. In proximal straight tubules neither the sodium-dependent nor the sodium-independent component of bicarbonate absorption was significantly affected by the acid-base status of the animals from which the tubules were obtained. .In cortical thick ascending limbs, chloride was absorbed, but there was no net transport of bicarbonate by tubules whether they came from acidotic or alkalotic animals. Since cortical thick ascending limbs were not found to transport bicarbonate, they cannot be implicated in the control of bicarbonate excretion. We conclude that the previously observed conditioning of bicarbonate transport occurs in collecting ducts but not in proximal straight tubules or in cortical thick ascending limbs in the same experimental situation.
在以往的研究中，当在标准体外条件下研究兔皮质集合管时，碳酸氢盐转运取决于获取肾小管的动物体内的酸碱状态。如果动物处于酸中毒状态（通过给予氯化铵），集合管会吸收碳酸氢盐，但如果动物处于碱中毒状态（通过给予碳酸氢钠），它们会分泌碳酸氢盐。本研究的目的是测试在其他肾单位节段是否发生类似的调节。在近端直小管中，获取肾小管的动物的酸碱状态对依赖钠和不依赖钠的碳酸氢盐吸收成分均无显著影响。在皮质厚升支中，氯化物被吸收，但无论肾小管来自酸中毒还是碱中毒的动物，均没有碳酸氢盐的净转运。由于未发现皮质厚升支转运碳酸氢盐，因此它们与碳酸氢盐排泄的控制无关。我们得出结论，在相同实验情况下，先前观察到的碳酸氢盐转运调节发生在集合管中，而不是近端直小管或皮质厚升支中。
