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In Japan, a range of patients with traumatic brain injury (TBI) has been recorded in a nationwide database (Japan Neurotrauma Data Bank; JNTDB). This study aimed to externally validate three international prediction models using JNTDB data: Trauma and Injury Severity Score (TRISS), Corticosteroid Randomization After Significant Head Injury (CRASH), and International Mission for Prognosis and Analysis of Clinical Trials in TBI (IMPACT). We also aimed to validate the applicability of these models in the Japanese population. Of 1,091 patients registered in the JNTDB from July 2009 to June 2011, we analyzed data for 635 patients. We examined factors associated with mortality in-hospital and unfavorable outcomes 6 months after TBI by applying the TRISS, CRASH, and IMPACT models. We also conducted an external validation of these models based on these data. The patients’ mean age was 60.1 ±21.1 years, and 342 were alive at the time of discharge (53.9%). Univariate analysis revealed eight major risk factors for mortality in-hospital: age, Glasgow Coma Scale (GCS), Injury Severity Score (ISS), systolic blood pressure, heart rate, mydriasis, acute epidural hematoma (AEDH), and traumatic subarachnoid hemorrhage. A similar analysis identified five risk factors for unfavorable outcomes at 6 months: age, GCS, ISS, mydriasis, and AEDH. For mortality in-hospital, the TRISS had a satisfactory area under the curve value (0.75). For unfavorable outcomes at 6 months, the CRASH (basic and computed tomography) and IMPACT (core and core extended) models had satisfactory area under the curve values (0.86, 0.86, 0.81, and 0.85, respectively). The TRISS, CRASH, and IMPACT models were suitable for application to the JNTDB population, indicating these models had high value in Japanese patients with neurotrauma. [ABSTRACT FROM AUTHOR]

Various studies have determined that the Great East Japan Earthquake (GEJE) caused mental distress among residents in affected areas. However, previous studies had not considered the prevalence of mental distress before the GEJE, and ignored the impact of an aged society on mental distress. Therefore, we aimed to describe the prevalence of mental distress before the GEJE in Miyagi Prefecture, Japan and elucidate the effect of an aged society on mental distress. We conducted an ecological study, using municipality in Miyagi Prefecture as the study unit. We used the cross-sectional mail survey data conducted in February 2011. We performed a correlation analysis in each of the 39 municipalities in Miyagi Prefecture. The prevalence of serious mental distress was 9.1%. The proportion of the population aged 65 years or older was related to the prevalence of serious mental distress in municipalities with a low proportion of all workers engaged in primary industry and with a high estimated number of inpatients with mental illness. We found that residents in Miyagi Prefecture suffered from poor mental health before the GEJE. Aged society was related to serious mental distress in the areas with advanced industrial structure and more patients with mental illness. We should approach mental health problems in the context of social structure, particularly in an aged society, based on facts about mental distress before the GEJE. [ABSTRACT FROM AUTHOR]

This study aims to use the conceptual framework of social determinants of health (SDH) to elucidate the social determinants that affect the use of complementary and alternative medicine (CAM) from the perspectives of both intermediary and structural determinants. Data were derived from a survey mailed to 1,500 randomly selected residents (20–69 years old; May–July 2009) of Sendai city in Japan. A generalized linear model was used in the analysis, with CAM use over the past one month as the dependent variable, SDH structural and intermediary determinants as independent variables, and demographic characteristics, indicators of health status, and the evaluation of health or healthcare systems as control variables. The prevalence of CAM usage was 62.1%. The generalized linear model showed that middle subjective social status (OR = 1.47; 95% CI: 1.04–2.07) as structural determinants was significantly associated with CAM usage. Adding the intermediary determinants, the same effect was observed. When demographic characteristics, indicators of health status, and the evaluation of health or healthcare systems were introduced as control variables, the associations of the structural determinants disappeared, revealing that hope (OR = 1.25; 95%CI: 1.04–1.50) as intermediary determinants was associated with the use of CAM. Female sex (OR = 1.47; 95% CI: 1.02–2.12) and health anxiety (OR = 1.68; 95% CI: 1.20–2.34) were associated with CAM usage. We found that intermediary rather than structural determinants were associated with CAM usage. Hope as an intermediary determinant was particularly associated with CAM usage. [ABSTRACT FROM AUTHOR]

Barttin, a gene product of BSND, is one of four genes responsible for Bartter syndrome. Coexpression of barttin with ClC-K chloride channels dramatically induces the expression of ClC-K current via insertion of ClC-K-barttin complexes into plasma membranes. We previously showed that stably expressed R8L barttin, a disease-causing missense mutant, is retained in the endoplasmic reticulum (ER) of Madin-Darby canine kidney (MDCK) cells, with the barttin β-subunit remaining bound to ClC-K α-subunits (Hayama A, Rai T, Sasaki S, Uchida S. Histochem Cell Biol 119: 485-493, 2003). However, transient expression of R8L barttin in MDCK cells was reported to impair ClC-K channel function without affecting its subcellular localization. To investigate the pathogenesis in vivo, we generated a knockin mouse model of Bartter syndrome that carries the R8L mutation. These mice display disease-like phenotypes (hypokalemia, metabolic alkalosis, and decreased NaCl reabsorption in distal tubules) under a low-salt diet. Immunofluorescence and immunoelectron microscopy revealed that the plasma membrane localization of both R8L barttin and the ClC-K channel was impaired in these mice, and transepithelial chloride transport in the thin ascending limb of Henle's loop (tAL) as well as thiazide-sensitive chloride clearance were significantly reduced. This reduction in transepithelial chloride transport in tAL, which is totally dependent on ClC-K1/barttin, correlated well with the reduction in the amount of R8L barttin localized to plasma membranes. These results suggest that the major cause of Bartter syndrome type IV caused by R8L barttin mutation is its aberrant intracellular localization. [ABSTRACT FROM AUTHOR]

The calcium-sensing receptor (CaSR) is known well as a sensor of extracellular calcium for regulating parathyroid hormone secretion. CaSR is located along all nephron segments in the kidney. While hypercalcemia strongly enhances urinary acidification, the relationship between CaSR and acid-base metabolism in the kidney is still uncertain. In the present study, we examined whether CaSR activation caused acid secretion in the medullary thick ascending limb (mTAL), which is one of the major nephron segments involved in both mineral and acid-base regulation. The effects of a potent calcimimetic neomycin (Neo) on intracellular pH (pHi) were analyzed in the in vitro miroperfused mouse mTALs. The mTALs were incubated with 2,7-bis-(2-carboxyethyl)-5(6)-carboxyfluoresceine-acetoxymethylester (BCECF-AM) for microfluorescent pHi measurements. In HCO3-/CO2-buffered solution, the steady-state pHi was 7.17 ± 0.01 (n = 19). Basolateral Neo at 0.4 mM in basolateral side significantly alkalinized the mTAL cells to 7.28 ± 0.02 (n = 19), while Neo in the lumen had no effect on pHi. Neo in the basolateral side alkalinized the mTALs in the absence of ambient Na+ and the presence of H+-ATPase inhibitor bafilomycin in the lumen, indicating that the effect of Neo is unrelated to Na+-dependent acid-base transporters such as Na+-H+ exchangers and Na+-HCO3- cotransporter, or to luminal H+-ATPase. In contrast, the effect of Neo on pHi was inhibited by K+ removal or treatment with specific H+-K+-ATPase (HKa) inhibitors, ouabain and Sch-28080Sch-28080, in the lumen. Our results suggest that hypercalcemia induces urinary acidification partly by stimulating luminal K+-dependent H+-excretion via CaSR in mouse mTALs. [ABSTRACT FROM AUTHOR]

The calcium-sensing receptor (CaSR) is known well as a sensor of extracellular calcium for regulating parathyroid hormone secretion. CaSR is located along all nephron segments in the kidney. While hypercalcemia strongly enhances urinary acidification, the relationship between CaSR and acid-base metabolism in the kidney is still uncertain. In the present study, we examined whether CaSR activation caused acid secretion in the medullary thick ascending limb (mTAL), which is one of the major nephron segments involved in both mineral and acid-base regulation. The effects of a potent calcimimetic neomycin (Neo) on intracellular pH (pHi) were analyzed in the in vitro microperfused mouse mTALs. The mTALs were incubated with 2,7-bis-(2-carboxyethyl)-5(6)-carboxyfluoresceine-acetoxy-methylester (BCECF-AM) for microfluorescent pHi measurements. In HCO3-/CO2-buffered solution, the steady-state pHi was 7.17 ± 0.01 (n = 19). Basolateral Neo at 0.4 mM in basolateral side significantly alkalinized the mTAL cells to 7.28 ± 0.02 (n = 19), while Neo in the lumen had no effect on pHi. Neo in the basolateral side alkalinized the mTALs in the absence of ambient Na+ and the presence of H+-ATPase inhibitor bafilomycin in the lumen, indicating that the effect of Neo is unrelated to Na+-dependent acid-base transporters such as Na+-H+ exchangers and Na+-HCO3- cotransporter, or to luminal H+-ATPase. In contrast, the effect of Neo on pHi was inhibited by K+ removal or treatment with specific H+-K+-ATPase (HKa) inhibitors, ouabain and Sch-28080Sch-28080, the lumen. Our results suggest that hypercalcemia induces urinary acidification partly by stimulating luminal K+-dependent H+-excretion via CaSR in mouse mTALs [ABSTRACT FROM AUTHOR]

Summary: WNK1 and WNK4 mutations have been reported to cause pseudohypoaldosteronism type II (PHAII), an autosomal-dominant disorder characterized by hyperkalemia and hypertension. To elucidate the molecular pathophysiology of PHAII, we generated Wnk4D561A/+ knockin mice presenting the phenotypes of PHAII. The knockin mice showed increased apical expression of phosphorylated Na-Cl cotransporter (NCC) in the distal convoluted tubules. Increased phosphorylation of the kinases OSR1 and SPAK was also observed in the knockin mice. Apical localization of the ROMK potassium channel and transepithelial Cl− permeability in the cortical collecting ducts were not affected in the knockin mice, whereas activity of epithelial Na+ channels (ENaC) was increased. This increase, however, was not evident after hydrochlorothiazide treatment, suggesting that the regulation of ENaC was not a genetic but a secondary effect. Thus, the pathogenesis of PHAII caused by a missense mutation of WNK4 was identified to be increased function of NCC through activation of the OSR1/SPAK-NCC phosphorylation cascade. [Copyright &y& Elsevier]

The extracellular calcium-sensing receptor (CaSR) located in either luminal or basolateral cell membranes of various types of renal tubules including proximal tubules, Henle's loop and collecting ducts has been thought to play a fundamental role in electrolyte metabolism. To further identify the physiological roles of the CaSR, we examined the effects of Ca2+ and calcimimetics neomycin (Neo), gentamicin and gadolinium chloride (Gd3+) on the intracellular pH (pHi) of in vitro microperfused mouse medullary thick ascending limb (mTAL) cells of Henle's loop, by loading the cells with fluorescent pH indicator 2′,7′-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein and measuring the ratio of fluorescence emission at 530 nm after exciting the dye at 490 and 440 nm. In a steady-state condition in Hepes-buffered solution, the pHi in the mTALs was 7.29 ± 0.04 (n = 9). A concentration of 200 µmol/l Neo in the basolateral side decreased the pHi after 1 min by -0.13 ± 0.02 (n = 34, p < 0.0001). The other calcimimetics showed similar effects on pHi, whereas none of these calcimimetics in the lumen affected pHi. Na+ removal or the inhibition of Na+ and proton transport with amiloride, bumetanide, or bafilomycin did not eliminate the effect of Neo on pHi. On the other hand, Cl. removal clearly eliminated the Neo-induced pHi decrease (-0.06 ± 0.01 vs -0.00 ± 0.05 in Cl. removal, n = 4, p < 0.003). Thus, we have demonstrated for the first time that the CaSR is involved in the regulation of the pHi in the mTAL and requires Cl. to exert its effect. [ABSTRACT FROM AUTHOR]

Analyzes the NaCl transport in thin ascending limb of Henle's loop in CLC-K1 null mice. Use of in vitro microperfusion of the tAL in the transport properties of sodium; Formation of concentrated urine by means of specific transport properties; Effects of protamine on the V[sub d] values in vitro microperfusion.

Background: While traditional, complementary and alternative medicine (TCAM) is gaining increased interest worldwide, the structural factors associated with the usage of TCAM at the social level have not been sufficiently explored. We aim to understand the social structure of uncertainty in society that affects the TCAM usage for men and women. Methods: We studied 32 countries using data from the International Social Survey Programme and the World Bank. In this study, we defined TCAM usage as visits to an alternative/traditional/folk health care practitioner during the past 12 months. We performed a correlation analysis and used a generalized linear model. Results: The prevalence of TCAM usage in terms of visits to practitioners was 26.1% globally, while usage varied across the 32 countries. Generalized linear models showed that unemployment rate was associated with the prevalence of TCAM usage in terms of visits to practitioners. Conclusions: At the social-structural level TCAM usage involving visits to practitioners was related to job insecurity. Job insecurity led to a decrease in TCAM usage regarding visits to practitioners. These findings suggest that it is necessary to consider the social-structural factors of uncertainty in society when designing health policies related to TCAM. [ABSTRACT FROM AUTHOR]

Congenital nephrogenic diabetes insipidus (NDI) is characterized by the inability of the kidney to concentrate urine. Congenital NDI is mainly caused by loss-of-function mutations in the vasopressin type 2 receptor (V2R), leading to impaired aquaporin-2 (AQP2) water channel activity. So far, treatment options of congenital NDI either by rescuing mutant V2R with chemical chaperones or by elevating cyclic adenosine monophosphate (cAMP) levels have failed to yield effective therapies. Here we show that inhibition of A-kinase anchoring proteins (AKAPs) binding to PKA increases PKA activity and activates AQP2 channels in cortical collecting duct cells. In vivo, the low molecular weight compound 3,3'-diamino-4,4'-dihydroxydiphenylmethane (FMP-API-1) and its derivatives increase AQP2 activity to the same extent as vasopressin, and increase urine osmolality in the context of V2R inhibition. We therefore suggest that FMP-API-1 may constitute a promising lead compound for the treatment of congenital NDI caused by V2R mutations.

Alport syndrome is a progressive renal disease caused by mutations in COL4A3, COL4A4, and COL4A5 genes that encode collagen type IV alpha 3, alpha 4, and alpha 5 chains, respectively. Because of abnormal collagen chain, glomerular basement membrane becomes fragile and most of the patients progress to end-stage renal disease in early adulthood. COL4A5 mutation causes X-linked form of Alport syndrome, and two mutations in either COL4A3 or COL4A4 causes an autosomal recessive Alport syndrome. Recently, renin-angiotensin-aldosterone system (RAAS) blockade has been shown to attenuate effectively disease progression in Alport syndrome. Here we present three Japanese siblings and their father all diagnosed with autosomal recessive Alport syndrome and with different clinical courses, suggesting the importance of the early initiation of RAAS blockade. The father was diagnosed with Alport syndrome. His consanguineous parents and his wife were healthy. All three siblings showed hematuria since infancy. Genetic analysis revealed that they shared the same gene mutations in COL4A3 in a compound heterozygous state: c.2330G>A (p.Gly777Ala) from the mother and c.4354A>T (p.Ser1452Cys) from the father. Although RAAS blockade was initiated for the older sister and brother when their renal function was already impaired, it did not attenuate disease progression. In the youngest brother, RAAS blockade was initiated during normal renal function stage. After the initiation, his renal function has been normal with the very mild proteinuria to date at the age of 17 years. We propose that in Alport syndrome, RAAS blockade should be initiated earlier than renal function is impaired.

Objective: A lower frequency for the peroxisome proliferator-activated receptor γ coactivator 1α (PPARGC1A) Ser482 allele has been reported in elite-level endurance athletes among Caucasians, although this gene polymorphism has not been found to be associated with aerobic capacity in German, Dutch or Chinese populations. The purpose of the current study was to examine the associations between the Gly482Ser polymorphism and aerobic fitness in 112 Japanese middle-aged men., Methods: The PPARGC1A Gly482Ser polymorphism was identified according to a TaqMan(®) SNP genotyping assay. Habitual physical activity was objectively measured using an accelerometer. The lactate threshold (LT), an index of aerobic fitness, was measured based on a submaximal graded exercise test performed on an electric cycle ergometer. The association between the LT and the Gly482Ser polymorphism was assessed according to a multiple regression analysis and analysis of covariance, with adjustment for potential confounders (age, body mass index, cigarette smoking, physical activity level and regular exercise)., Results: A significant association was observed between the PPARGC1A Gly482Ser polymorphism and LT, as carriers of the Ser482 had higher LT values than the Gly482 carriers., Conclusion: The current results suggest that the PPARGC1A Ser482 allele is associated with a higher aerobic capacity in Japanese middle-aged men.

K(+) channels permit more than one ion within their conducting pathway at any given moment and show a saturating single-file behavior. The conduction of Rb(+) shows an unusual behavior, a so-called "Rb(+) anomaly," and it has been used to probe the mechanism of the ion conduction through K(+)-selective channels. Under the bi-ionic condition of K(+) and Rb(+), we carried out patch-clamp single-channel current measurements in MaxiK(+) channels from mouse submandibular acinar cells. Keeping only K(+) on one side of the membrane while varying fractional Rb(+) concentration on the opposite, we had a series of current-voltage relationships. It showed a characteristic inflection at which the ion conductance was divided into two components, one ascribed to pure K(+) conduction and the other to K(+) and Rb(+) bi-ionic conduction. By analyzing the latter, we depicted that (1) the bi-ionic conductance showed a characteristic reduction curve as the Rb(+) fractional concentration increased; (2) Rb(+) can bind the channel more tightly when it accesses from the outside than from the inside. Thus we conclude that such asymmetry of the Rb(+) binding determines the pattern of bi-ionic conductance reduction in K-selective channels.

The calcium-sensing receptor (CaSR) is known well as a sensor of extracellular calcium for regulating parathyroid hormone secretion. CaSR is located along all nephron segments in the kidney. While hypercalcemia strongly enhances urinary acidification, the relationship between CaSR and acid-base metabolism in the kidney is still uncertain. In the present study, we examined whether CaSR activation caused acid secretion in the medullary thick ascending limb (mTAL), which is one of the major nephron segments involved in both mineral and acid-base regulation. The effects of a potent calcimimetic neomycin (Neo) on intracellular pH (pHi) were analyzed in the in vitro miroperfused mouse mTALs. The mTALs were incubated with 2,7-bis-(2-carboxyethyl)-5(6)-carboxyfluoresceine-acetoxymethylester (BCECF-AM) for microfluorescent pHi measurements. In HCO(3)(-)/CO(2)-buffered solution, the steady-state pHi was 7.17 +/- 0.01 (n = 19). Basolateral Neo at 0.4 mM in basolateral side significantly alkalinized the mTAL cells to 7.28 +/- 0.02 (n = 19), while Neo in the lumen had no effect on pHi. Neo in the basolateral side alkalinized the mTALs in the absence of ambient Na(+) and the presence of H(+)-ATPase inhibitor bafilomycin in the lumen, indicating that the effect of Neo is unrelated to Na(+)-dependent acid-base transporters such as Na(+)-H(+) exchangers and Na(+)-HCO(3)(-) cotransporter, or to luminal H(+)-ATPase. In contrast, the effect of Neo on pHi was inhibited by K(+) removal or treatment with specific H(+)-K(+)-ATPase (HKa) inhibitors, ouabain and Sch-28080, in the lumen. Our results suggest that hypercalcemia induces urinary acidification partly by stimulating luminal K(+)-dependent H(+)-excretion via CaSR in mouse mTALs.

To examine whether the functional and morphologic conversion of the neonatal ascending thin limb (ATL) of Henle's loop is related to gestational length, we evaluated the transepithelial voltages (Vts) of ATLs in perinatal mouse, hamster, rabbit, and rat kidneys. In isolated microperfused tubule preparations, Vts of neonatal ATLs were 23.8 +/- 1.4 in mouse, 25.7 +/- 2.2 in hamster, and 18.2 +/- 1.6 mV in rabbit. The influence of gestational length on the Vts and rat Na-K-Cl cotransporter (rNKCC2) expression pattern was also examined in perinatal rats subjected to a prolonged gestation due to either a daily s.c. injection of 5 mg progesterone or ligation of the extremities of the uterine horn. Vts of d 3 neonates were 2.9 +/- 1.0 (p < 0.0001 versus d 0); Vts of d 23 fetuses subjected to ligation were 4.9 +/- 0.8 (p < 0.005 versus d 0); and Vts of d 23 fetuses given progesterone were 3.4 +/- 1.7 mV (p < 0.001 versus d 0). rNKCC2 expression tended to disappear in the renal papillae of d 23 fetuses. Our data demonstrate that the perinatal conversion of the ATL is a phenomenon commonly observed among rodents; furthermore, it is dependent on the gestational length, but unrelated to the birth process.

We investigated the association between stroke and blood pressure (BP) indices (systolic BP [SBP], diastolic BP [DBP], mean BP [MBP], and pulse pressure [PP]) determined by ambulatory BP monitoring. The predictive power for stroke of these indices was compared in the general Japanese population. We obtained ambulatory BP data in 1271 subjects (40% men) aged > or = 40 (mean: 61) years. During a mean follow-up of 11 years, 113 strokes were observed. The multivariate adjusted relative hazard and likelihood ratio for a 1-SD increase for each BP index was determined by Cox proportional hazard regression. Comparison of the likelihood ratio between Cox models including 2 indices and those including 1 index indicated that PP was significantly less informative than other indices (P<0.01 when adding MBP, SBP, or DBP to the PP model; P>0.09 when adding PP to the model including another index). However, after removing age from covariates, PP became more informative than DBP and MBP (P<0.0001 when adding PP to the MBP or DBP model, whereas SBP was more informative than PP even after removing age; P<0.05 when adding SBP to the PP model). In conclusion, PP was the weakest predictor of stroke. Exclusion of age from covariates increased the predictive power of PP, suggesting that the stroke risk associated with PP reflected the risk of aging per se.

The charge selectivity (CS) function in human renal disease has not been unequivocally demonstrated to date. However, the clearance ratio of IgA to IgG may be theoretically useful in estimating CS in humans, since IgA and IgG have similar sizes and tertiary structures, but distinct isoelectric points (3.5-5.5 [IgA] and 4.5-9.0 [IgG]), and Stokes-Einstein radius: 61 A (IgA) and 49-60 A (IgG). Two-dimensional electrophoresis with the following immunoblotting revealed that the considerably anionic portion (isoelectric points [pI] <4.0) of IgA, visible in serum, was absent in the urine in steroid-sensitive nephrotic syndrome (SSNS) but present in the same during IgA nephropathy (IgAN) and membranoproliferative glomerulonephritis (MPGN). A latex assay revealed the CS index (CSI) was significantly low in patients with podocyte disease (group A), including SSNS, focal and segmental glomerulosclerosis (FSGS) and Finnish-type congenital nephrotic syndrome (FCNS), but high in those with Alport syndrome (AS), IgAN, Henoch-Schönlein purpura nephritis (HSPN), and MPGN (group B). The linear regression analysis of the IgA size selectivity index (IgA SSI; clearance ratio of IgA to transferrin) and SSI (clearance ratio of IgG to transferrin), which represents the clearance ratio of IgA to IgG referring to the transferrin clearance, revealed the influence of the charge more accurately. Indeed, the slope of the regression lines of IgA SSI (y) to SSI (x) were concluded to be y = 0.39x (group A) and y = 1.05x (group B), respectively. These results suggested that the charge selective barrier among podocyte diseases (group A) is preserved to some degree, but lost in cases of nephritis and AS (group B).

Polyphenols are ubiquitous plant metabolites with multiple pharmacological properties. Using whole-cell patch-clamp current recording techniques, we studied the effects of polypnenols extracted from red wine (purity > 90% from Cabernet Sauvignon grape wine) on the activities of voltage-operated Na+-, K+-, and Ca2+-channel currents in mouse dorsal root ganglionic neuronal cells. The polyphenols suppressed all of the channel activities with half-effective concentrations of about 2.5, 4.0, and 0.8-1.5 micro g/ml, respectively. In contrast, they showed no noticeable effects on the ion channels in other types of cells, including large conductance K+-channels in mouse lacrimal acinar cells. Thus, the polyphenols suppress firings of the action potential in the neuronal cells and could show a sedative effect on the excitation. We expect that red wine can be used as a remedy for excessive sensory stimuli.

To characterize the nature of NaCl transport in the thin ascending limb (tAL), we examined the transport properties of Na(+) and Cl(-) using in vitro microperfusion of the tAL in CLC-K1 null mice. In the presence of a transmural NaCl concentration gradient (100 mM higher in the lumen), the transepithelial diffusion voltage (V(d)) was 15.5 +/- 1.0 and -7.6 +/- 1.4 mV in CLC-K1(+/+) and CLC-K1(-/-) mice, respectively. Neither Cl(-) transport inhibitor 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) nor acidification of the bathing fluid changed the V(d) values in CLC-K1(-/-) mice. The addition of 300 microg/ml protamine, a selective blocker of paracellular conductance, to the bath increased the V(d) values by 5.6 +/- 0.7 and 12.6 +/- 1.5 mV (P < 0.001) in CLC-K1(+/+) and CLC-K1(-/-) mice, respectively. Although efflux coefficients of (36)Cl were significantly decreased in CLC-K1(-/-) mice (188.3 +/- 25.6 in 4 tubules vs. 17.2 +/- 7.0 x 10(-5) cm/s in 6 tubules), those of (22)Na were not different between CLC-K1(+/+) and CLC-K1(-/-) mice. These results clearly indicate that the major component of Cl(-) transport sensitive to NPPB or pH is mediated by CLC-K1 in the tAL.