Furuya H, Breyer M D, Jacobson H R
Department of Medicine, Vanderbilt University, Nashville, Tennessee.
Am J Physiol. 1991 Sep;261(3 Pt 2):F377-85. doi: 10.1152/ajprenal.1991.261.3.F377.
Single-cell electrical measurements and spectrophotometric determinations of intracellular pH were used to determine unique features of alpha- and beta-intercalated cells (alpha-IC, beta-IC) in in vitro perfused rabbit cortical collecting ducts (CCD). pHi rose in alpha-IC and fell in beta-IC after bath Cl- removal. Luminal Cl- removal did not change pHi of alpha-IC, but pHi of beta-IC rose by 0.36 +/- 0.01 pH units. Cl- concentration-dependent recovery of beta-IC pHi revealed a Cl- Km of 18.7 mM for the luminal Cl(-) -HCO3- exchanger. Measurements of basolateral membrane voltage (Vbl) also showed two IC cell types. Removal of luminal Cl- did not change Vbl in alpha-IC, whereas Vbl hyperpolarized by a mean of 73.2 +/- 3.5 mV in beta-IC. Reducing bath Cl- depolarized both alpha- and beta-IC Vbl. In alpha-IC a large repolarization of 39.8 +/- 5.2 mV followed acute depolarization after bath Cl- removal. Reducing bath HCO3- (constant CO2) had little effect on beta-IC Vbl, whereas alpha-IC Vbl depolarized by 5.2 +/- 0.7 mV. Reducing luminal HCO3- in the absence of luminal Cl- produced a 17.6 +/- 1.8 mV depolarization in beta-IC. This change was independent of luminal Na+ and was not blocked by luminal 10(-4) M 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). In beta-IC, Vbl was not altered by either bath or lumen DIDS in the presence of luminal Cl-. However, when luminal Cl- was removed, luminal DIDS reversibly depolarized Vbl by 9.6 +/- 2.9 mV.(ABSTRACT TRUNCATED AT 250 WORDS)
采用单细胞电测量和细胞内pH分光光度测定法，来确定体外灌注兔皮质集合管（CCD）中α-和β-闰细胞（α-IC，β-IC）的独特特征。去除浴液中的Cl-后，α-IC中的细胞内pH（pHi）升高，而β-IC中的pHi降低。去除管腔Cl-不会改变α-IC的pHi，但β-IC的pHi升高0.36±0.01pH单位。β-IC的pHi的Cl-浓度依赖性恢复显示，管腔Cl(-)-HCO3-交换体的Cl-米氏常数为18.7mM。基底外侧膜电压（Vbl）的测量也显示出两种闰细胞类型。去除管腔Cl-不会改变α-IC中的Vbl，而β-IC中的Vbl平均超极化73.2±3.5mV。降低浴液Cl-会使α-IC和β-IC的Vbl去极化。在α-IC中，去除浴液Cl-后急性去极化后会出现39.8±5.2mV的大幅复极化。降低浴液HCO3-（恒定CO2）对β-IC的Vbl影响很小，而α-IC的Vbl去极化5.2±0.7mV。在无管腔Cl-的情况下降低管腔HCO3-会使β-IC出现17.6±1.8mV的去极化。这种变化与管腔Na+无关，且不受管腔10(-4)M 4,4'-二异硫氰基芪-2,2'-二磺酸（DIDS）的阻断。在β-IC中，在存在管腔Cl-的情况下，浴液或管腔DIDS均不会改变Vbl。然而，当去除管腔Cl-时，管腔DIDS会使Vbl可逆地去极化9.6±2.9mV。（摘要截短于250字）
