BICARBONATE TRANSPORT ALONG THE LOOP OF HENLE .1. MICROPERFUSION STUDIES OF LOAD AND INHIBITOR SENSITIVITY
BICARBONATE TRANSPORT ALONG THE LOOP OF HENLE .1. MICROPERFUSION STUDIES OF LOAD AND INHIBITOR SENSITIVITY
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DOI：
10.1172/jci115322
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发表时间：
1991-08-01
影响因子：
15.9
通讯作者：
GIEBISCH, G
中科院分区：
文献类型：
--
作者：
CAPASSO, G;UNWIN, R;GIEBISCH, G
我们对Henle袢（洛）进行微灌注，以评估其对体内尿液酸化的贡献。 在对照条件下（NaHCO 3- = 13 mM，灌注速率约为17 nl/min-1），净碳酸氢盐转运（JHCO 3-）是不饱和的，流量和浓度依赖性，线性增加，直到碳酸氢盐负荷为1，400 pmol。达到min-1。 醋甲唑胺（2 . 10（-4）M）使JHCO 3减少70%;阿米洛利类似物乙基异丙基阿米洛利（EIPA）（2 . 10（~ 4 M）使JHCO 3减少40%;醋甲唑胺和EIPA均不影响净水通量（Jv）。 H+-ATP酶抑制剂巴弗洛霉素A1（10（-5）M）使JHCO 3减少20%; Cl-通道抑制剂5-硝基-2 '-（3-苯基丙基氨基）-苯甲酸酯（2 . 10（-4）M）和Cl--碱交换抑制剂二异硫氰酸基-2，2 '-芪二磺酸盐（5 . 10（-5）M），对碳酸氢盐重吸收分数没有影响。 布美他尼（10（-6）M）刺激碳酸氢盐转运（净和部分JHCO 3-）20%，而呋塞米（10（-4）M）对碳酸氢盐重吸收没有影响;两种利尿剂都降低了Jv。总之：（a）洛对尿酸化有显著作用。 它通常重吸收相当于15%过滤的碳酸氢盐的量;（B）碳酸氢盐重吸收不饱和;（c）Na+-H+交换和ATP依赖性质子泵主要负责大部分洛丢失碳酸氢盐转运。
We microperfused the loop of Henle (LOH) to assess its contribution to urine acidification in vivo. Under control conditions (NaHCO3- = 13 mM, perfusion rate approximately 17 nl/min-1) net bicarbonate transport (JHCO3-) was unsaturated, flow- and concentration-dependent, and increased linearly until a bicarbonate load of 1,400 pmol . min-1 was reached. Methazolamide (2 . 10(-4) M) reduced JHCO3 by 70%; the amiloride analogue ethylisopropylamiloride (EIPA) (2 . 10(-4 M) reduced JHCO3 by 40%; neither methazolamide nor EIPA affected net water flux (Jv). The H+-ATPase inhibitor bafilomycin A1 (10(-5) M) reduced JHCO3 by 20%; the Cl- channel inhibitor 5-nitro-2'-(3-phenylpropylamino)-benzoate (2 . 10(-4) M) and the Cl--base exchange inhibitor diisothiocyanato-2,2'-stilbenedisulfonate (5 . 10(-5) M), had no effect on fractional bicarbonate reabsorption. Bumetanide (10(-6) M) stimulated bicarbonate transport (net and fractional JHCO3-) by 20%, whereas furosemide (10(-4) M) had no effect on bicarbonate reabsorption; both diuretics reduced Jv.In summary: (a) the LOH contributes significantly to urine acidification. It normally reabsorbs an amount equivalent to 15% of filtered bicarbonate; (b) bicarbonate reabsorption is not saturated; (c) Na+-H+ exchange and an ATP-dependent proton pump are largely responsible for the bulk of LOH bicarbonate transport.