Importance of anion in hypotonic volume regulation of rabbit proximal straight tubule.
Importance of anion in hypotonic volume regulation of rabbit proximal straight tubule.
复制标题
阴离子在兔近曲小管低渗容量调节中的重要性。
DOI：
10.1152/ajprenal.1988.255.5.f853
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Linshaw,MA
中科院分区：
文献类型：
--
作者：
Welling,PA;Linshaw,MA
当突然浸入低渗介质中时，家兔近端直小管迅速膨胀至最大体积。然而，在第二个较慢的阶段，称为容量调节性减少（VRD），由于钾离子、伴随的阴离子和水的流出，肾小管向其基础体积收缩。在本研究中，我们调查的性质，阴离子在低渗容量调节。我们去除Cl和/或HCO 3缓冲液以评估它们在VRD中的相对重要性，并且我们使用呋塞米、4-乙酰氨基-4 '-异硫氰基芪-2，2'-二磺酸（SITS）和钡来研究VRD中跨膜阴离子途径的性质。用葡萄糖酸盐等渗置换小管周围Cl对等渗介质中的小管体积或低渗介质中的初始渗透压溶胀反应均无影响。然而，VRD在这样的Cl-耗尽小管显着抑制。对照组肾小管在稀释培养基中调节至低于其最大体积的81%。相比之下，Cl耗尽的小管调节只有39%。这种抑制作用不能归因于没有管周氯或葡萄糖酸盐的存在。不存在HCO 3缓冲液或存在SITS（0.5 mM）对VRD的速率或程度没有抑制作用。单独的呋塞米（1 mM）对VRD也没有抑制作用。然而，尽管单独使用钡剂可以延迟VRD，但在钡剂处理的小管中加入呋塞米可以进一步减缓其最大液体流出率，并进一步延迟VRD。（250字处删节）
Rabbit proximal straight tubules rapidly swell to a maximum volume when abruptly immersed into hypotonic medium. However, in a second, slower phase, termed volume regulatory decrease (VRD), tubules shrink toward their basal volume due to the efflux of K, accompanying anion and water. In the present study, we investigated the nature of the anion during hypotonic volume regulation. We removed Cl and/or the HCO3 buffer to assess their relative importance in VRD, and we used furosemide, 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS), and barium to investigate the nature of the transmembrane anion pathway in VRD. Isosmotic replacement of peritubular Cl with gluconate had no effect on either tubule volume in isotonic medium or the initial osmometric swelling response in hypotonic medium. However, the VRD in such Cl-depleted tubules was significantly inhibited. Control tubules regulated 81% below their maximal volume in dilute medium. By contrast, Cl-depleted tubules regulated only 39%. This inhibitory effect could not be attributed to the absence of peritubular Cl or to the presence of gluconate. The absence of the HCO3 buffer or the presence of SITS (0.5 mM) had no inhibitory effect on the rate or extent of VRD. Furosemide alone (1 mM) also had no inhibitory effect on VRD. However, whereas barium alone delays VRD, addition of furosemide to barium-treated tubules further slowed their maximal rate of fluid efflux and delayed VRD even more.(ABSTRACT TRUNCATED AT 250 WORDS)