Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P41181 (collecting duct)
 5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To evaluate the effect of furosemide on kidney function, glomerular filtration rate (GFR), urinary Na excretion (UNaV), Na reabsorption (NAR), and Na+-K+-ATPase in isolated nephron segments were measured in 1) rats treated with furosemide 10 mg X 100 g-1 X 24 h-1 ip for 7 days, and 2) rats receiving an oral Na load for 12 days. In furosemide-treated rats, GFR rose from 0.61 +/- 0.03 (mean +/- SD) to 0.83 +/- 0.06 ml/min (P less than 0.01), UNaV rose from 904 +/- 71 to 1,402 +/- 85 mueq/day (P less than 0.001), and net NAR rose from 87.5 +/- 3.7 to 116.7 +/- 9.0 mueq/min (P less than 0.01). Na+-K+-ATPase remained unchanged in the proximal convoluted tubule (PCT), proximal straight tubule (PST), cortical thick ascending limb of Henle's loop (cTALH), and medullary thick ascending limb of Henle's loop (mTALH), but was increased in the distal convoluted tubule (DCT) and in cortical collecting duct (CCD) from 48.5 +/- 1.2 to 75.3 +/- 0.7 (P less than 0.001) and from 18.6 +/- 0.7 to 27.1 +/- 2.7 (P less than 0.02) X 10(-11) mol X mm-1 X min-1, respectively. In Na-loaded rats GFR rose from 0.61 +/- 0.04 to 0.86 +/- 0.03 ml/min (P less than 0.001), UNaV rose from 1,064 +/- 118 to 18,532 +/- 2,045 mueq/day (P less than 0.001), net NAR from 88.1 +/- 3.0 to 107.8 +/- 3.9 mueq/min and Na-K-ATPase in the mTALH rose from 40.3 +/- 1.4 to 56.2 +/- 2.11 (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Enhanced glomerular filtration and Na+-K+-ATPase with furosemide administration. 303 78

Na-K-ATPase activity was determined in seven nephron segments of five-week-old, spontaneously hypertensive rats (SHR) with or without continuous hydrochlorothiazide (HCTZ) treatment for seven days. For comparison, the effects of HCTZ treatment on Na-K-ATPase activity in the nephron segments of age-matched normotensive Wistar-Kyoto rats (WKY) were also determined. Na-K-ATPase activity in proximal convoluted tubule (PCT), medullary thick ascending limb (MTAL), cortical thick ascending limb (CTAL), distal convoluted tubule (DCT) and cortical collecting duct (CCD) was significantly lower in HCTZ-treated SHR compared to control (untreated) SHR. However, there was no significant difference in Na-K-ATPase activity in proximal straight tubule (PST) and medullary collecting duct (MCD) between HCTZ-treated and control SHR. HCTZ treatment also produced a significant decrease in blood pressure (BP) and creatinine clearance (CCr) in SHR. On the other hand, HCTZ treatment did not produce a significant change in Na-K-ATPase activity in PCT, PST, MTAL, CTAL and MCD, in BP or in CCr in WKY. However, HCTZ treatment produced a decrease in the enzyme activity in the DCT and an increase in the enzyme activity in the CCD in WKY. The decrease in Na-K-ATPase activity in almost all nephron segments from SHR may be due to a significant decrease in CCr produced by HCTZ. On the other hand, a decrease in Na-K-ATPase activity in the DCT with an increase in the enzyme activity in the CCD from WKY suggest that renal compensation to the natriuretic effect of HCTZ occurs by an increase in Na+ reabsorption in the CCD.
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PMID:Effects of hydrochlorothiazide on Na-K-ATPase activity along the rat nephron. 303 68

Aldosterone enhances synthesis and enzyme activity of Na/K-ATPase and has been found to stimulate sodium reabsorption by the renal cortical collecting duct. Moreover, chronic exposure to aldosterone is associated with a remarkable morphological-functional adaptation. This is seen as a magnification in basolateral membrane area of principal cells. In the present paper we investigated the acquistion of Na/K-ATPase alpha-subunit in renal tissue and examined whether aldosterone initiates functional and adaptive changes in cultured collecting duct cells similar to those observed in vivo. Using a monoclonal antibody, immunofluorescence microscopy demonstrated the acquisition of the alpha-subunit of Na/K-ATPase in the developing cortical collecting ducts of the kidney of neonatal rabbits. The mature collecting ducts in the medulla and papilla of the developing kidney were strongly labelled at the basolateral side, while in the cortical portion of the fetal collecting duct adjacent to the embryonic ampullae the immunolabel was found at the apical and the basolateral aspect of the epithelium. However, the embryonic collecting duct ampullae in the outer cortex did not show any reaction with the antibody. In the collecting duct cells cultured for 24 hours the alpha-subunit of Na/K-ATPase was found to be distributed at both the apical and basolateral aspect of the epithelium. After two to 16 days, the immunolabel was strictly found distributed at the basolateral side. Culturing collecting duct cells in the presence of aldosterone (10(-6) M), the hormone modulated the cellular shape of epithelia after five days by infolding the lateral plasma membranes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Expression of the alpha-subunit of Na/K-ATPase in renal collecting duct epithelium during development. 303 56

Na-K-ATPase activity in the connecting tubule (CNT) and cortical collecting duct (CCD) has been shown to be influenced by KCl both in the presence and in the absence of aldosterone. To investigate if the aldosterone-independent effect of K+ on Na-K-ATPase can be produced by other K+ salts, we studied the effects of dietary KHCO3 on Na-K-ATPase and ouabain-insensitive Mg-ATPase activities in four nephron segments of adrenalectomized (ADX) rabbits. The segments examined were: the distal convoluted tubule (DCT), CNT, CCD and medullary collecting duct (MCD). All diets were similar in composition except their KHCO3 contents which were 100, 300, 500 and 700 meq/kg in groups 1 to 4 respectively. Increasing KHCO3 in the diet increased K+ excretion (7 X) and urine pH (6.6 to 8.3). Na-K-ATPase activity in the CCD increased greater than 200% as dietary KHCO3 was increased to 700 meq/kg. There was a linear relation between Na-K-ATPase activity in this segment and steady state plasma K+ as well as K+ excretion in the urine. However, Na-K-ATPase activity in the CCD was lower in KHCO3-fed ADX rabbits than the KCl-fed animals studied previously under similar conditions. There were no significant differences in Na-K-ATPase activities in DCT, CNT and MCD among the four groups given different KHCO3-diets. It is concluded that dietary intake of KHCO3 can also influence Na-K-ATPase activity in the CCD independent of aldosterone.
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PMID:Effects of potassium bicarbonate on distal nephron Na-K-ATPase in adrenalectomized rabbits. 303 48

The morphologically heterogeneous cell populations in the collecting ducts of the rat kidney were studied using immunocytochemical detection of Na+-K+-ATPase and the anion channel (band 3) glycoprotein. Both enzymes were localized to the basal aspect of separate and morphologically distinct subpopulations of cells in various segments of the collecting duct. Na+-K+-ATPase appeared to be present exclusively in principal cells as identified by their morphology, whereas band 3 antibodies reacted only with intercalated cells. However, 5-20% of cells with the morphological characteristics of intercalated cells failed to react with either antisera in various segments of collecting ducts. As band 3 glycoprotein serves in exchanging intracellular bicarbonate for chloride, it is highly likely that the cells positive for this antigen secrete protons. The method introduced here appears thus useful for distinguishing between principal and intercalated cells by differences in their enzyme content and further for revealing two subpopulations of intercalated cells. This method promises to provide a useful approach for studying the principal and intercalated cell populations in various metabolic states.
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PMID:Three distinct cell populations in rat kidney collecting duct. 303 55

The relationship between structure and function in the distal tubule and collecting duct has been studied with morphologic and physiologic techniques, including morphometric analysis, to identify functionally distinct cell populations. The distal tubule, including the thick ascending limb (TAL) and the distal convoluted tubule (DCT), is involved in active reabsorption of sodium chloride. It is characterized by extensive invaginations of the basolateral plasma membrane, numerous mitochondria, and high Na-K-ATPase activity, features characteristic for an epithelium involved in active transport. Between the distal tubule and the collecting duct is a transition region, the connecting segment or the connecting tubule (CNT), which exhibits species differences with respect to both structure and function. The collecting duct includes the cortical (CCD), the outer medullary (OMCD), and the inner medullary (IMCD) collecting ducts. Principal cells are present throughout the collecting duct, whereas intercalated cells are located mainly in the CCD and OMCD. Morphometric analysis combined with micropuncture and microperfusion studies has provided evidence that the CNT and principal cells are responsible for potassium secretion in the connecting segment and the CCD. The OMCD is a main site of hydrogen ion secretion, and morphometric studies have provided evidence that the intercalated cells in this segment secrete hydrogen ion at least in the rat. Two configurations of intercalated cells exist in the CCD--a type A and a type B. The A cells are similar in ultrastructure to the intercalated cells in the OMCD and are believed to be involved in hydrogen ion secretion. The function of the B cells remains to be established. The inner two-thirds of the IMCD corresponds to the papillary collecting duct, which has a high permeability to urea. The relationship between structure and function in the IMCD has not been studied in detail. This review emphasizes the role of morphometric analysis in establishing the relationship between structure and function in the distal nephron.
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PMID:Relationship between structure and function in distal tubule and collecting duct. 305 90

Rat renal papillary collecting duct (PCD) cells were isolated using collagenase and hyaluronidase digestion and a three-step low-speed centrifugation. As assessed by binding of the lectin Dolichos biflorus and determination of vasopressin-sensitive adenylate cyclase and Na+-K+-ATPase, the enrichment of PCD cells over a crude papillary cell preparation was 1.8, 2.4, and 1.4, respectively. Microscopic evaluation indicated that the preparation was greater than 90% pure PCD cells. The isolated cells were viable as evident from the high K/Na ratio of intracellular electrolytes measured by electron probe analysis (5.3), from the high ATP/ADP ratio (2.15), and the metabolic response to alterations in Na transport. Exposure to 2 mM ouabain or removal of Na reduced O2 consumption by 25-35%; the uncoupler carboxylcyanide-m-chlorophenylhydrazone more than doubled O2 consumption. In the presence of 14 mM glucose and at a PO2 of 100 Torr the cells produced substantial quantities of lactate. This aerobic glycolysis may account for greater than 20% of the ATP production. In the presence of rotenone, glycolysis increased by 56% and was able to maintain the cellular ATP level at 65% of control. In the absence of any exogenous substrate PCD cells respired normally and had a close to normal ATP content, but lactate production was markedly decreased. These results demonstrate that viable PCD cells can be isolated from rat kidney. At normal PO2 and in the presence of D-glucose the cells show a substantial amount of aerobic glycolysis, although their mitochondrial respiration is not rate limiting. In the absence of glucose the cells derive the majority of their energy from an as yet unidentified endogenous substrate.
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PMID:Purification of rat papillary collecting duct cells: functional and metabolic assessment. 330 74

Sodium transport in the papillary collecting duct (PCD) is poorly understood because of the inaccessibility of the distal nephron to micropuncture. Cultured rat renal papillary collecting tubule (RPCT) cells were investigated as a model for the PCD. RPCT cells have the morphologic appearance and hormonal responsiveness of the papillary collecting tubule. Sodium transport was studied using 22Na+ uptake measurements. Sodium uptake, measured at 23 degrees C in the absence of K+ and in the presence of 0.5 mM ouabain, was saturable at 100 mM extracellular NaCl, and half-maximal uptake occurred at 40 mM NaCl. The accumulation of 22Na+ appeared to be intracellular and was regulated by (Na+,K+)-ATPase activity, since activation of the Na+/K+ pump with K+ reduced 22Na+ accumulation by 90%. The time course for uptake was linear, showed only a single component, and followed first order kinetics with a t1/2 of 16 min. Amiloride and lithium inhibited 22Na+ influx, and a Dixon plot was linear, with a Ki of 16 microM amiloride. Chloride replacement of 1 mM furosemide, with or without K+, reduced uptake by only 20%. Sodium efflux from RPCT cells in the presence of ouabain showed a similar time course (t1/2, 15 min) and was also inhibited by amiloride (IC50 = 20 microM). Increased extracellular pH stimulated 22Na+ uptake and inhibited 22Na+ efflux. Addition of permeable organic acids, acetate, and bicarbonate, enhanced 22Na+ uptake. These results are consistent with Na+/H+ and Na+/Na+ exchange as mechanisms of 22Na+ uptake in the RPCT cell. This exchanger may be important in regulation of transepithelial sodium flux, maintenance of intracellular pH and cell volume, and hormonal stimulation of the papillary collecting duct.
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PMID:Sodium transport in rat renal papillary collecting tubule cells in culture. 337 95

The distal tubule, which includes the thick ascending limb (TAL), the macula densa, and the distal convoluted tubule (DCT), and the collecting duct are structurally heterogeneous, thus reflecting the functional heterogeneity that is also present. As the TAL ascends from medulla to cortex, the surface area of the apical plasma membrane increases while that of the basolateral membrane decreases. The structure of the DCT resembles that of the medullary TAL. An excellent correlation exists between structure, Na-K-ATPase activity, and NaCl reabsorptive capacity in the distal tubule. The collecting duct is subdivided into the initial collecting tubule (ICT), and cortical (CCD), outer medullary (OMCD), and inner medullary (IMCD) collecting ducts. Between the distal tubule and the collecting duct is a transition region termed the connecting segment or connecting tubule (CNT). Considerable structural heterogeneity exists along the collecting duct within the two major cell populations, the intercalated cells and the principal cells. In the CNT, the ICT, and the CCD, potassium loading and mineralocorticoids stimulate Na-K-ATPase activity and cause proliferation of the basolateral membrane of CNT cells and principal cells, thus identifying the cells responsible for mineralocorticoid-stimulated potassium secretion in these regions. Finally, at least two morphologically distinct populations of intercalated cells exist, types A and B. In the rat, type A predominates in the CNT and the OMCD and is believed to be responsible for H+ secretion, at least in the OMCD. Type B predominates in the CCD, where it may be involved in bicarbonate secretion.
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PMID:Structural-functional relationships along the distal nephron. 351 May 62

The distal tubule, which includes the thick ascending limb (TAL), the macula densa, and the distal convoluted tubule (DCT), and the collecting duct are structurally heterogeneous, thus reflecting the functional heterogeneity that is also present. As the TAL ascends from medulla to cortex, the surface area of the apical plasma membrane increases while that of the basolateral membrane decreases. The structure of the DCT resembles that of the medullary TAL. An excellent correlation exists between structure, Na-K-ATPase activity, and NaCl reabsorptive capacity in the distal tubule. The collecting duct is subdivided into the initial collecting tubule (IC), and cortical (CCD), outer medullary (OMCD), and inner medullary (IMCD) collecting ducts. Between the distal tubule and the collecting duct is a transition region termed the connecting segment or connecting tubule (CNT). Considerable structural heterogeneity exists along the collecting duct within the two major cell populations, the intercalated cells and the principal cells. In the CNT, the ICT, and the CCD, potassium loading and mineralocorticoids stimulate Na-K-ATPase activity and cause proliferation of the basolateral membrane of CNT cells and principal cells, thus identifying the cells responsible for mineralocorticoid-stimulated potassium secretion in these regions. Finally, at least two morphologically distinct populations of intercalated cells exist, types A and B. In the rat, type A predominates in the CNT and the OMCD and is believed to be responsible for H+ secretion, at least in the OMCD. Type B predominates in the CCD, where it may be involved in bicarbonate secretion.
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PMID:Structural-functional relationship along the distal nephron. 352 38


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