Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cultured inner medullary collecting duct (IMCD) cells have been shown to secrete protons (H+) by two mechanisms: an N-ethylmaleimide- and dicyclohexyl-carbodiimide-sensitive electrogenic H(+)-ATPase or H+ pump, and an amiloride-sensitive, secondary active Na+H+ exchanger. These cells also express Cl-/HCO3- exchange and carbonic anhydrase activity in common with other renal epithelial cells involved in acid-base transport. Video fluorescence microscopy of individual cells using 2',7'-biscarboxyethyl-5(6)-carboxyfluorescein has demonstrated that adjacent-cultured IMCD cells show substantial functional intercellular heterogeneity. The development of H(+)-pumping activity is associated with high-baseline intracellular pH and peanut agglutinin (PNA) affinity, and loss of mitotic activity and of Na+/H+ exchange. The H(+)-pumping activity may be further enhanced by removal of fetal calf serum for 6-54 h or by selecting cells with high PNA affinity. IMCD cells in their most differentiated state form domes, which consistently showed the highest rates of H(+)-pumping activity, as well as high affinity for peanut lectin. When IMCD were plated at low density, domes developed relatively late (2-4 weeks), at which time cells located in the center of nests of contiguously growing cells were quiescent and showed H(+)-pumping activity but no Na+/H+ exchange. On the other hand, dense plating was associated with early development of domes (end of 1st week), at which time adjacent cells showed a high mitotic activity and Na+/H+ exchange, but no H(+)-pumping activity. We speculate that differentiation of IMCD cells results in the development of cell polarity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differentiation of proton-pumping activity in cultured renal inner medullary collecting duct cells. 216 49

This study was conducted to determine the effect of feeding vitamin D3(D3) metabolites on BW of hen, weight of uterus, plasma Ca, jejunal and uterine adenosine triphosphatase (ATPase), and carbonic anhydrase. At 416 days of age each of 7 groups of laying hens was fed the basal ration supplemented with one of 7 concentrations (micrograms per kg) of D3 or its metabolites as treatments: 0 micrograms of D3; 27.5 micrograms of D3; 3, 5, or 7 micrograms of 1,25(OH)2D3; 5 micrograms of 24,25(OH)2D3; and 5 micrograms of 24,25(OH)2D3 plus 5 micrograms of 1,25(OH)2D3. Treatment effects were compared at various periods after the start of the study. Hens fed the unsupplemented ration had lower (P less than .05) values for all traits than hens fed the D3-supplemented ration by 162 days after the start of treatment. In a comparison of all dietary treatments except the one involving 0 micrograms D3, from 154 to 161 days after the start of the experiment, treatment effects were significant (P less than or equal to .05) for BW, uterine ATPase, and carbonic anhydrase; hens fed 5 micrograms of 24,25(OH)2D3 per kg of ration ranked the lowest of all treatment groups for these traits. Hens fed 27.5 micrograms of D3 and those fed 5 micrograms of 1,25(OH)2D3 per kg of ration did not differ (P greater than .05) for any traits studied. The results suggest that 5 micrograms of 1,25(OH)2D3 per kg of ration can replace 27.5 micrograms of D3 per kg of ration but that 5 micrograms of 24,25(OH)2D3 per kg of ration tends to have a negative effect on physiological systems of the hen.
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PMID:Effects of vitamin D3 metabolites on physiological traits of White Leghorn hens. 217 50

The apical membrane of the rabbit corneal endothelium contains a potassium-selective ionic channel. In patch-clamp recordings, the probability of finding the channel in the open state (Po) depends on the presence of either HCO3- or Cl- in the bathing medium. In a methane sulfonate-containing bath, Po is less than 0.05 at all physiologically relevant transmembrane voltages. With 0 mM [HCO3-]o at +60 mV, Po was 0.085 and increased to 0.40 when [HCO3-]o was 15 mM. With 4 mM [Cl-]o at +60 mV, Po was 0.083 and with 150 mM Cl-, Po increased to 0.36. Low Po's are also found when propionate, sulphate, bromide, and nitrate are the primary bath anions. The mechanism of action of the anion-stimulated K+ channel gating is not yet known, but a direct action of pH seems unlikely. The alkalinization of cytoplasm associated with the addition of 10 mM (NH4)2SO4 to the bath and the acidification accompanying its removal do not result in channel activation nor does the use of Nigericin to equilibrate intracellular pH with that of the bath over the pH range of 6.8 to 7.8. Channel gating also is not affected by bathing the internal surface of the patch with cAMP, cGMP, GTP-gamma-s, Mg2+ or ATP. Blockers of Na/H+ exchange, Na(+)-HCO3- cotransport, Na(+)-K+ ATPase and carbonic anhydrase do not block the HCO3- stimulation of Po. Several of the properties of the channel could explain some of the previously reported voltage changes that occur in corneal endothelial cells stimulated by extracellular anions.
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PMID:Potassium channel in rabbit corneal endothelium activated by external anions. 231 91

Stimulation or inhibition of H+ secretion has been associated with characteristic ultrastructural changes in various epithelial cells, including the parietal cell of the gastric mucosa, the carbonic anhydrase (CA)-rich cell of the turtle urinary bladder, and the intercalated (I) cell of the mammalian collecting duct. An electroneutral potassium-activated H+-ATPase is responsible for H+ secretion in the stomach, whereas acidification in the turtle bladder and the mammalian collecting duct is mediated by an electrogenic H+-translocating ATPase. Despite these differences, the parietal cell, the CA-rich cell, and the I cell have several morphological features in common. They are rich in mitochondria, contain numerous tubulovesicular membrane structures in the apical region of the cell, and possess a variable number of microprojections on the luminal surface. After stimulation of H+ secretion there is a significant increase in the surface area of the apical membrane concomitant with a decrease in the tubulovesicular membrane compartment in these cells, as revealed by morphometric analysis. These findings suggest that membrane (possibly containing an H+ pump) is being transferred from the tubulovesicular compartment to the apical plasma membrane on stimulation of H+ secretion. A hypothesis of membrane recycling is proposed to account for the observed morphological changes.
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PMID:Structure-function relationships in H+-secreting epithelia. 241 Feb 97

The histochemical and cytochemical localization of carbonic anhydrase activity in the inner ear of guinea pig was studied with Hansson's method and modified Yokota's method. All cells possessing the cell membrane infoldings are proved to have the enzymatic activity. The cochlear hair cells show strong enzymatic activity while the vestibular hair cells show no appreciable activity. The supporting cells of both cochlear and vestibular hair cells also show the enzymatic activity. The reaction products showing the enzymatic activity are observed in the cytoplasm, nucleus and cell membrane of the stained cells with both light microscope and electron microscope. The stria vascularis, vestibular dark cells and endolymphatic sac are proved to have the enzymatic activity. The cells, which are already proved to have Na+-K+-ATPase activity, show the enzymatic activity. The regulation of the fluid and ion in the inner ear is probably a complex mechanism involving not only various cells but also several enzymes such as carbonic anhydrase, Na+-K+-ATPase and adenylate cyclase.
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PMID:Carbonic anhydrase activity in the inner ear. 241 Nov 4

The elasmobranch rectal gland has served as a useful model to study features of Na-K-Cl cotransport that are common to many chloride-transporting epithelia. These include: (1) dependence on a Na+ gradient created by Na-K-ATPase; (2) high intracellular Cl- concentration; (3) characteristic inhibitor profile including inhibition by loop diuretics and barium but not by amiloride, SITS, DIDS, or carbonic anhydrase inhibitors; and (4) remarkable energy efficiency of transepithelial transport (25-30 NaCl/l 02). The mechanism by which this is accomplished is clarified by kinetic analysis of experiments with isolated perfused rectal glands of Squalus acanthias in which perfusate concentrations of Na and Cl are systematically varied. These show a Hill coefficient of one for Na+ and two for Cl-, suggesting that one Na+, one K+, and two Cl- interact with the cotransport carrier. Nitrate can substitute for Cl- to some extent, and it itself weakly transported. The loop diuretic bumetanide behaves like a competitive inhibitor of Cl-. The teleological significance of the neutral cotransport of two Cl- with one Na+ and one K+ is that it enables transporting epithelia like the rectal gland, cornea, salivary gland, and thick ascending limb of Henle's loop to double the efficiency of their Na-K-ATPase pump.
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PMID:Na-K-Cl cotransport in chloride-transporting epithelia. 241 26

Immunocytochemical detection of carbonic anhydrase (CA II), (Na+-K+)-ATPase and the anion channel (band 3) glycoprotein was used to study structural and functional heterogeneity of cells lining the collecting ducts, especially of intercalated cells, in the rat kidney. High content of CA II was found in intercalated cells as determined by morphology, although a weak diffuse cytoplasmic staining of this enzyme could be observed also in a subpopulation of principal cells. (Na+-K+)-ATPase could be detected exclusively in principal cells, whereas basolateral band 3 immunoreactivity was seen only in a subpopulation of intercalated cells. Double immunostaining experiments revealed that the weak cytoplasmic type of CA II and basolateral (Na+-K+)-ATPase immunoreactivities were colocalized in 20 to 30% (depending on the segment studied) of the collecting duct epithelial cells but, in contrast, cells rich in CA II or those with basal band 3 immunoreactivity seldom contained (Na+-K+)-ATPase. Instead, band 3 glycoprotein and the abundant CA II were colocalized in 20 to 35% of the cells in various segments of collecting ducts, whereas, band 3 and weak cytoplasmic CA II were seldom seen in the same cells. The results show that the current approach is useful for identifying and characterizing two distinct subpopulations of intercalated cells, both rich in CA II but differing in respect to the presence or absence of band 3 glycoprotein. On the basis of physiologic and biochemical data of the functions of these transport proteins we propose that the subpopulations of intercalated cells thus identified represent the acidifying and alkalinizing subtypes, respectively.
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PMID:Immunocytochemical characterization of carbonic anhydrase-rich cells in the rat kidney collecting duct. 244 Nov 37

A subepithelial multilayer of abundant fusiform cells has been distinguished cytochemically in the urinary bladder and ureter in mice and rats. These distinctive cells stained selectively for carbonic anhydrase (CA) isozymes I and III. Immunonegativity for keratin and Na+,K+-ATPase differentiated the CA-positive cells from epithelial cells and their lack of immunoreactivity for actin distinguished them from smooth muscle cells. Immunostaining for vimentin, blue staining with the trichrome method, location in an exceptionally dense collagen stroma, and ultrastructural appearance related the multilayer cells to fibroblasts. A loosely collagenous, less cellular lamina propria separated the CA-positive suburothelial zone from the smooth muscle wall in the rodent urinary bladder. Ureter lacked the loose lamina propria, and the presence of such a collageneous layer in bladder therefore correlated with distensability of the organ. The presence of CA uniquely in the fibroblastoid cells applied intimately to ureter and bladder epithelium implies a specialized function of these cells, possibly one concerned with the barrier between blood and hypertonic urine. Cytochemical demonstration of keratin and fucose-rich glycoconjugate in the plasmalemma of superficial urothelial cells indicates a role for these components in passively maintaining the blood-urine barrier. The observed distribution of Na+,K+-ATPase in mid and deep urothelial cells implicates this enzyme and these cells in actively maintaining the urine's hypertonicity. Basal urothelial cells contained glycoconjugate with terminal galactose in their plasmalemma. Ultrastructural features suggesting involution of superficial urothelial cells further evidence restriction of active ion transport to the deeper cells.
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PMID:Evidence for the blood-urine barrier depending on urothelium and carbonic anhydrase positive fibroblasts. 244 48

With immunocytochemistry, we have determined distribution of sodium, potassium-adenosine triphosphatase (Na+, K+-ATPase) and of three isoenzymes of carbonic anhydrase (CA) and have shown absence of the chloride channel, Band 3 protein, in the genital tract of female rodents. Staining for Na+,K+-ATPase was strongest in the ampullary oviduct and uterine glands in the mouse. In the mouse and rat ovary, immunostaining evidenced CA I, II, and III in theca interna cells where the enzyme could affect the pH of follicular fluid. The zona pellucida of the ovary and cytoplasmic foci in follicular granulosa cells stained for content of only CA I in mouse ovary, suggesting synthesis of a zona pellucida component by granulosa cells. CA II in mouse oviductal epithelium increased from the negative infundibulum to the variably positive ampulla and isthmus to the uniformly positive interstitial segment. The content of CA III varied inversely to that of CA II. The prevalence of CA II-positive cells apparently corresponded with that of nonciliated cells, whereas abundance of CA III-positive cells concurred with that of ciliated cells in regions of the mouse oviduct. The rat oviduct lacked CA II but, like that of the mouse, showed CA III in the proximal region. The staining for CA II in surface epithelium exceeded the reactivity in glandular epithelium in the mouse uterus, except during estrus. In contrast, rat uterus evidenced CA II in glandular but not surface epithelium. These results testify to possible significance of various ion transport mechanisms for biologic activities of diverse cells in the female genital tract.
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PMID:Immunocytochemistry of ion transport mediators in the genital tract of female rodents. 245 38

The localization of carbonic anhydrase by histochemistry, of Na-K-ATPase by immunocytochemistry and of rod-shaped intramembranous particles by freeze-fracture electron microscopy, was determined in the collecting duct of rabbits. In the cortical collecting duct (CCD), rod-shaped particles, which are abundant in intercalated cells were observed in both the apical and basolateral membrane of all intercalated cells examined. In the outer stripe of the outer medullary collecting duct (OMCDo) a high density of rod-shaped particles was found only in the apical membrane of intercalated cells. All cells of the inner stripe of the outer medullary collecting duct (OMCDi) had rod-shaped particles in the apical membrane but not in the basolateral membrane. As the collecting duct entered the inner medulla the density of rod-shaped particles decreased until they were virtually absent in the terminal segment. Na-K-ATPase, localized to the basolateral membrane, was more abundant in principal cells than in intercalated cells in the CCD. In the OMCDo, staining was equal in principal and intercalated cells. All cells of the OMCDi and the inner medullary collecting duct (IMCD) stained for Na-K-ATPase. Carbonic anhydrase in the CCD was localized to the cell membranes and cytoplasm of intercalated cells. Principal cells did not stain for carbonic anhydrase. A similar pattern was seen in the OMCDo. In the outer region of the OMCDi most cells did not stain for carbonic anhydrase, whereas in the inner region the apical and lateral membranes of all cells stained for carbonic anhydrase. Weak cytoplasmic staining was occasionally seen. A similar pattern was seen in the initial half of the IMCD, while the terminal half of the IMCD did not stain. In this study, the localization of enzymes and rod-shaped intramembranous particles associated with Na+, K+, and H+ transport shows both segmental and cellular heterogeneity, and correlates with the known transport properties of tubule segments. The distribution of these enzymes and rod-shaped intramembranous particles is different in rabbits and rats, and may explain some of the functional differences between homologous segments in these species.
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PMID:Morphological heterogeneity of the rabbit collecting duct. 246 75


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