1
|
Méndez E, Caruso Neves C, López Mañanes A. Two sodium pumps in the hepatopancreas of the intertidal euryhaline crab Neohelice granulata: biochemical characteristics and differential modulation after feeding. CAN J ZOOL 2018. [DOI: 10.1139/cjz-2017-0128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
No study has been done on the existence, biochemical characteristics, and modulation of K+-independent ouabain-insensitive Na+ ATPase activity (the second sodium pump) in the digestive tract of intertidal euryhaline crabs and moreover on the coexistence and modulation under distinct physiological and (or) environmental conditions of different sodium pumps. We determined the occurrence, characteristics, and responses at different times (0, 1, 24, 48, and 120 h) after feeding upon distinct salinities of Na+ ATPase activity and Na+/K+ ATPase in the hepatopancreas of Neohelice granulata (Dana, 1851), which is a model species. The stimulation by Na+ under total inhibition of Na+/K+ ATPase activity revealed the occurrence of Na+ ATPase activity that was totally inhibited by 2 mmol·L–1 furosemide, exhibits Michaelis–Menten kinetics for ATP (apparent Km = 0.52 ± 0.16 mmol·L–1), and highest activity at around pH 7.4. In crabs acclimated to 35 psu (osmoconforming conditions), Na+ ATPase activity was highly increased (about 15-fold) (532 ± 58 nmol Pi·mg protein−1·min−1) in the hepatopancreas 48 h after feeding. In 10 psu (hyper-regulating conditions), Na+ ATPase activity decreased in the hepatopancreas 24 h after feeding (7 ± 9 nmol Pi·mg protein−1·min−1) and recovered initial values after 48 h (24 ± 35 nmol Pi·mg protein−1·min−1). Unlike Na+ ATPase, Na+/K+ ATPase activity did not change after feeding at any salinity, suggesting the specific modulation of the second sodium pump and its role in postprandial adjustments in the hepatopancreas.
Collapse
Affiliation(s)
- E. Méndez
- Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) – Universidad Nacional de Mar del Plata, Funes 3250, Mar del Plata, Argentina
| | | | - A.A. López Mañanes
- Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) – Universidad Nacional de Mar del Plata, Funes 3250, Mar del Plata, Argentina
| |
Collapse
|
2
|
Is the second sodium pump electrogenic? BIOMED RESEARCH INTERNATIONAL 2013; 2013:698674. [PMID: 23484143 PMCID: PMC3591133 DOI: 10.1155/2013/698674] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 11/11/2012] [Accepted: 11/22/2012] [Indexed: 12/02/2022]
Abstract
Transepithelial sodium transport is a process that involves active Na+ transport at the basolateral membrane of the epithelial cell. This process is mediated by the Na+/K+ pump, which exchanges 3 internal Na+ by 2 external K+ inducing a net charge movement and the second Na+ pump, which transports Na+ accompanied by Cl− and water. It has been suggested that this pump could also be electrogenic. Herein, we evaluated, in MDCK cells, the short-circuit current (Isc) generated by these Na+ pumps at the basolateral membrane of the epithelial cells, using amphotericin B as an apical permeabilizing agent. In Cl−-containing media, Isc induced by amphotericin B is totally inhibited by ouabain, indicating that only the electrogenic Na+/K+ pump is detectable in the presence of Cl−. Electrogenicity of the second Na+ pump can be demonstrated in Cl−-free media. The existence of a furosemide-sensitive component of Isc, in addition to an ouabain-sensitive one, was identified in absence of chloride. Passive Cl− movement associated with the function of the second Na+ pump seems to be regulated by the pump itself. These results demonstrate that the second Na+ pump is an electroneutral mechanism result from the stoichiometric movement of Na+ and Cl− across the basolateral plasma membrane of the epithelial cell.
Collapse
|
3
|
Rocafull MA, Thomas LE, del Castillo JR. The second sodium pump: from the function to the gene. Pflugers Arch 2012; 463:755-77. [PMID: 22543357 PMCID: PMC3350626 DOI: 10.1007/s00424-012-1101-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 03/22/2012] [Accepted: 03/24/2012] [Indexed: 11/30/2022]
Abstract
Transepithelial Na(+) transport is mediated by passive Na(+) entry across the luminal membrane and exit through the basolateral membrane by two active mechanisms: the Na(+)/K(+) pump and the second sodium pump. These processes are associated with the ouabain-sensitive Na(+)/K(+)-ATPase and the ouabain-insensitive, furosemide-inhibitable Na(+)-ATPase, respectively. Over the last 40 years, the second sodium pump has not been successfully associated with any particular membrane protein. Recently, however, purification and cloning of intestinal α-subunit of the Na(+)-ATPase from guinea pig allowed us to define it as a unique biochemical and molecular entity. The Na(+)- and Na(+)/K(+)-ATPase genes are at the same locus, atp1a1, but have independent promoters and some different exons. Herein, we spotlight the functional characteristics of the second sodium pump, and the associated Na(+)-ATPase, in the context of its role in transepithelial transport and its response to a variety of physiological and pathophysiological conditions. Identification of the Na(+)-ATPase gene (atna) allowed us, using a bioinformatics approach, to explore the tertiary structure of the protein in relation to other P-type ATPases and to predict regulatory sites in the promoter region. Potential regulatory sites linked to inflammation and cellular stress were identified in the atna gene. In addition, a human atna ortholog was recognized. Finally, experimental data obtained using spontaneously hypertensive rats suggest that the Na(+)-ATPase could play a role in the pathogenesis of essential hypertension. Thus, the participation of the second sodium pump in transepithelial Na(+) transport and cellular Na(+) homeostasis leads us to reconsider its role in health and disease.
Collapse
Affiliation(s)
- Miguel A. Rocafull
- Laboratorio de Fisiología Molecular, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (IVIC), Apartado 20632, Caracas, 1020A Venezuela
| | - Luz E. Thomas
- Laboratorio de Fisiología Molecular, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (IVIC), Apartado 20632, Caracas, 1020A Venezuela
| | - Jesús R. del Castillo
- Laboratorio de Fisiología Molecular, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (IVIC), Apartado 20632, Caracas, 1020A Venezuela
| |
Collapse
|
4
|
Gámez AD, Gutiérrez AM, García R, Whittembury G. Recent experiments towards a model for fluid secretion in Rhodnius Upper Malpighian Tubules (UMT). JOURNAL OF INSECT PHYSIOLOGY 2012; 58:543-550. [PMID: 22206885 DOI: 10.1016/j.jinsphys.2011.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 12/08/2011] [Accepted: 12/14/2011] [Indexed: 05/31/2023]
Abstract
Three different methods have been used to improve a model for fluid secretion in Upper Malpighian Tubules (UMT) of the blood sucking insect Rhodnius prolixus. (I) In the first, UMT double perfusions in 5th instar Rhodnius were used to measure their fluid secretion rate. They were stimulated to secrete with 5-HT. Double perfusions allowed access separately to the basolateral and the apical cell membranes with pharmacological agents known to block different ion transport functions, namely ATPases, cotransporters and/or countertransporters and ion and water channels: ouabain, bafilomycin A1, furosemide, bumetanide, SITS, acetazolamide, amiloride, DPC, BaCl(2), pCMBS and DTT. The basic assumption is that changes in water movement reflect changes in ion transport mechanisms. (II) Intracellular Na(+) concentrations were measured with a fluorometric method in dissected R. prolixus UMT, under several experimental conditions. (III) ATPase activities were measured in R. prolixus UMT. A tentative model for the function of the UMT cell is presented. We find that (a) at the basolateral cell membrane, fundamental is a Na(+)-K(+)-2Cl(-) cotransporter; of intermediate importance are the Na(+)-K(+)-ATPase and a ouabain-insensitive Na(+)-ATPase, ion channels and Rp-MIP water channels. (b) At the apical cell membrane, most important are a V-H(+)-ATPase; and a K(+) and/or Na(+)-H(+) exchanger.
Collapse
Affiliation(s)
- Adriana D Gámez
- Instituto Venezolano de Investigaciones Científicas, Universidad Central de Venezuela, Caracas, Venezuela.
| | | | | | | |
Collapse
|
5
|
Liu W, Schreck C, Coleman RA, Wade JB, Hernandez Y, Zavilowitz B, Warth R, Kleyman TR, Satlin LM. Role of NKCC in BK channel-mediated net K⁺ secretion in the CCD. Am J Physiol Renal Physiol 2011; 301:F1088-97. [PMID: 21816753 DOI: 10.1152/ajprenal.00347.2011] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Apical SK/ROMK and BK channels mediate baseline and flow-induced K secretion (FIKS), respectively, in the cortical collecting duct (CCD). BK channels are detected in acid-base transporting intercalated (IC) and Na-absorbing principal (PC) cells. Although the density of BK channels is greater in IC than PC, Na-K-ATPase activity in IC is considered inadequate to sustain high rates of urinary K secretion. To test the hypothesis that basolateral NKCC in the CCD contributes to BK channel-mediated FIKS, we measured net K secretion (J(K)) and Na absorption (J(Na)) at slow (∼1) and fast (∼5 nl·min(-1)·mm(-1)) flow rates in rabbit CCDs microperfused in vitro in the absence and presence of bumetanide, an inhibitor of NKCC, added to the bath. Bumetanide inhibited FIKS but not basal J(K), J(Na), or the flow-induced [Ca(2+)](i) transient necessary for BK channel activation. Addition of luminal iberiotoxin, a BK channel inhibitor, to bumetanide-treated CCDs did not further reduce J(K). Basolateral Cl removal reversibly inhibited FIKS but not basal J(K) or J(Na). Quantitative PCR performed on single CCD samples using NKCC1- and 18S-specific primers and probes and the TaqMan assay confirmed the presence of the transcript in this nephron segment. To identify the specific cell type to which basolateral NKCC is localized, we exploited the ability of NKCC to accept NH(4)(+) at its K-binding site to monitor the rate of bumetanide-sensitive cytosolic acidification after NH(4)(+) addition to the bath in CCDs loaded with the pH indicator dye BCECF. Both IC and PC were found to have a basolateral bumetanide-sensitive NH(4)(+) entry step and NKCC1-specific antibodies labeled the basolateral surfaces of both cell types in CCDs. These results suggest that BK channel-mediated FIKS is dependent on a basolateral bumetanide-sensitive, Cl-dependent transport pathway, proposed to be NKCC1, in both IC and PC in the CCD.
Collapse
Affiliation(s)
- Wen Liu
- Division of Pediatric Nephrology, Department of Pediatrics, Mount Sinai School of Medicine, New York, New York 10029, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Rocafull MA, Romero FJ, Thomas LE, del Castillo JR. Isolation and cloning of the K+-independent, ouabain-insensitive Na+-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1684-700. [PMID: 21334305 DOI: 10.1016/j.bbamem.2011.02.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 01/17/2011] [Accepted: 02/11/2011] [Indexed: 10/18/2022]
Abstract
Primary Na+ transport has been essentially attributed to Na+/K+ pump. However, there are functional and biochemical evidences that suggest the existence of a K+-independent, ouabain-insensitive Na+ pump, associated to a Na+-ATPase with similar characteristics, located at basolateral plasma membrane of epithelial cells. Herein, membrane protein complex associated with this Na+-ATPase was identified. Basolateral membranes from guinea-pig enterocytes were solubilized with polyoxyethylene-9-lauryl ether and Na+-ATPase was purified by concanavalin A affinity and ion exchange chromatographies. Purified enzyme preserves its native biochemical characteristics: Mg2+ dependence, specific Na+ stimulation, K+ independence, ouabain insensitivity and inhibition by furosemide (IC50: 0.5 mM) and vanadate (IC50: 9.1 μM). IgY antibodies against purified Na+-ATPase did not recognize Na+/K+-ATPase and vice versa. Analysis of purified Na+-ATPase by SDS-PAGE and 2D-electrophoresis showed that is constituted by two subunits: 90 (α) and 50 (β) kDa. Tandem mass spectrometry of α-subunit identified three peptides, also present in most Na+/K+-ATPase isoforms, which were used to design primers for cloning both ATPases by PCR from guinea-pig intestinal epithelial cells. A cDNA fragment of 1148 bp (atna) was cloned, in addition to Na+/K+-ATPase α1-isoform cDNA (1283 bp). In MDCK cells, which constitutively express Na+-ATPase, silencing of atna mRNA specifically suppressed Na+-ATPase α-subunit and ouabain-insensitive Na+-ATPase activity, demonstrating that atna transcript is linked to this enzyme. Guinea-pig atna mRNA sequence (2787 bp) was completed using RLM-RACE. It encodes a protein of 811 amino acids (88.9 kDa) with the nine structural motifs of P-type ATPases. It has 64% identity and 72% homology with guinea-pig Na+/K+-ATPase α1-isoform. These structural and biochemical evidences identify the K+-independent, ouabain-insensitive Na+-ATPase as a unique P-type ATPase.
Collapse
Affiliation(s)
- Miguel A Rocafull
- Laboratorio de Fisiología Molecular, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
| | | | | | | |
Collapse
|
7
|
Rocafull MA, Thomas LE, Barrera GJ, Castillo JRD. Differential expression of P-type ATPases in intestinal epithelial cells: Identification of putative new atp1a1 splice-variant. Biochem Biophys Res Commun 2010; 391:152-8. [PMID: 19900414 DOI: 10.1016/j.bbrc.2009.11.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Accepted: 11/03/2009] [Indexed: 11/28/2022]
Affiliation(s)
- Miguel A Rocafull
- Lab. Fisiología Molecular, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Apartado 20632, Caracas 1020-A, Venezuela.
| | | | | | | |
Collapse
|
8
|
Na(+)-ATPase in spontaneous hypertensive rats: possible AT(1) receptor target in the development of hypertension. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1798:360-6. [PMID: 19560439 DOI: 10.1016/j.bbamem.2009.06.018] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 06/16/2009] [Accepted: 06/19/2009] [Indexed: 01/01/2023]
Abstract
Clinical and experimental data show an increase in sodium reabsorption on the proximal tubule (PT) in essential hypertension. It is well known that there is a link between essential hypertension and renal angiotensin II (Ang II). The present study was designed to examine ouabain-insensitive Na(+)-ATPase activity and its regulation by Ang II in spontaneously hypertensive rats (SHR). We observed that Na(+)-ATPase activity was enhanced in 14-week-old but not in 6-week-old SHR. The addition of Ang II from 10(-12) to 10(-6) mol/L decreased the enzyme activity in SHR to a level similar to that obtained in WKY. The Ang II inhibitory effect was completely reversed by a specific antagonist of AT(2) receptor, PD123319 (10(-8) mol/L) indicating that a system leading to activation of the enzyme in SHR is inhibited by AT(2)-mediated Ang II. Treatment of SHR with losartan for 10 weeks (weeks 4-14) prevents the increase in Na(+)-ATPase activity observed in 14-week-old SHR. These results indicate a correlation between AT(1) receptor activation in SHR and increased ouabain-insensitive Na(+)-ATPase activity. Our results open new possibilities towards our understanding of the pathophysiological mechanisms involved in the increased sodium reabsorption in PT found in essential hypertension.
Collapse
|
9
|
Thomas LE, Burguillos L, del Castillo JR. Backdoor phosphorylation of basolateral plasma membranes of small intestinal epithelial cells: characterization of a furosemide-induced phosphoprotein related to the second sodium pump. Arch Biochem Biophys 2003; 419:190-7. [PMID: 14592462 DOI: 10.1016/j.abb.2003.08.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Enterocyte has two different Na+-stimulated ATPases, the ouabain-sensitive Na+/K+ ATPase and a furosemide-inhibitable Na+ ATPase. To identify the polypeptide associated with the Na+-ATPase, 32Pi phosphorylation into basolateral membranes of enterocyte was investigated. Both, ouabain and furosemide induced Mg2+-dependent, vanadate-sensitive 32Pi incorporation into a 100kDa polypeptide. K(m) for Pi was 17.7+/-1.82 microM and 16.8+/-0.69 microM for ouabain-induced and furosemide-induced phosphorylation, respectively. K(m) for furosemide was 1.3+/-0.21 mM. Furosemide-induced 32Pi incorporation was sensitive to alkaline pH and hydroxylamine suggesting an acyl-phosphate bond. Na+ and K+ inhibited 32Pi incorporation induced by ouabain. In contrast, Na+ stimulated furosemide-induced phosphorylation with a K(m) of 16.5+/-5.59 mM while K+ had no effect. Purified Na+/K+ ATPase only presented ouabain-induced phosphoprotein, indicating that furosemide-induced phosphorylation is not related to this enzyme and appears to correspond to a new member of P-type ATPases associated with the second Na+ pump.
Collapse
Affiliation(s)
- Luz E Thomas
- Laboratorio de Fisiología Gastrointestinal, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (IVIC), Apartado 21827, 1020-A Caracas, Venezuela
| | | | | |
Collapse
|
10
|
Gal-Garber O, Mabjeesh SJ, Sklan D, Uni Z. Nutrient transport in the small intestine: Na+,K+-ATPase expression and activity in the small intestine of the chicken as influenced by dietary sodium. Poult Sci 2003; 82:1127-33. [PMID: 12872969 DOI: 10.1093/ps/82.7.1127] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Na+-K+-ATPase, localized in the basolateral membrane of enterocytes plays a major role in nutrient transport in the small intestine by transferring K+ ions into and Na+ out of the cell. Within the enterocyte, homeostasis is maintained by active exclusion of Na from the cell by the Na+,K+-adenosine triphosphatase (ATPase) or sodium pump. Because much of the intestinal nutrient transport is by Na cotransporters, Na+,K+-ATPase may be used to evaluate nutrient uptake. In this study, nutrient transport was evaluated by determining expression and activity of Na+-K+-ATPase in the jejunum of chicks fed diets with different concentrations of Na. Expression of the chicken Na+-K+-ATPase gene was examined following isolation of an 1,140 bp cDNA fragment of the alpha-subunit using a reverse transcription (RT)-PCR reaction with specific primers. This fragment was sequenced and showed 95 to 98% homology with the mammalian alpha-subunit of the Na+-K+-ATPase genes. This cDNA fragment was used as a specific probe in Northern blot hybridization for determination of expression in the chicken jejunum. Expression of mRNA of Na+-K+-ATPase was enhanced at low dietary Na but was unchanged at high dietary Na concentrations. In contrast, activity of the enzyme was low with low dietary Na and unchanged at high dietary Na. The Vmax of the Na+-K+-ATPase was unchanged, but affinity was altered by dietary Na concentrations. Thus, determination of expression and activity of intestinal Na+-K+-ATPase allows clearer understanding of changes in intestinal uptake due to dietary Na.
Collapse
Affiliation(s)
- O Gal-Garber
- Department of Animal Sciences, Faculty of Agricultural Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 76100 Israel
| | | | | | | |
Collapse
|
11
|
Caruso-Neves C, Coelho-Souza SA, Vives D, Goes G, Lara LS, Lopes AG. Modulation of ouabain-insensitive Na(+)-ATPase activity in the renal proximal tubule by Mg(2+), MgATP and furosemide. Int J Biochem Cell Biol 2002; 34:1586-93. [PMID: 12379280 DOI: 10.1016/s1357-2725(02)00059-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In addition to the (Na(+)+K(+))ATPase another P-ATPase, the ouabain-insensitive Na(+)-ATPase has been observed in several tissues. In the present paper, the effects of ligands, such as Mg(2+), MgATP and furosemide on the Na(+)-ATPase and its modulation by pH were studied in the proximal renal tubule of pig. The principal kinetics parameters of the Na(+)-ATPase at pH 7.0 are: (a) K(0.5) for Na(+)=8.9+/-2.2mM; (b) K(0.5) for MgATP=1.8+/-0.4mM; (c) two sites for free Mg(2+): one stimulatory (K(0.5)=0.20+/-0.06 mM) and other inhibitory (I(0.5)=1.1+/-0.4 mM); and (d) I(0.5) for furosemide=1.1+/-0.2 mM. Acidification of the reaction medium to pH 6.2 decreases the apparent affinity for Na(+) (K(0.5)=19.5+/-0.4) and MgATP (K(0.5)=3.4+/-0.3 mM) but increases the apparent affinity for furosemide (0.18+/-0.02 mM) and Mg(2+) (0.05+/-0.02 mM). Alkalization of the reaction medium to pH 7.8 decreases the apparent affinity for Na(+) (K(0.5)=18.7+/-1.5 mM) and furosemide (I(0.5)=3.04+/-0.57 mM) but does not change the apparent affinity to MgATP and Mg(2+). The data presented in this paper indicate that the modulation of the Na(+)-ATPase by pH is the result of different modifications in several steps of its catalytical cycle. Furthermore, they suggest that changes in the concentration of natural ligands such as Mg(2+) and MgATP complex may play an important role in the Na(+)-ATPase physiological regulatory mechanisms.
Collapse
Affiliation(s)
- C Caruso-Neves
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, CCS Bloco G, 21949 Rio de Janeiro (RJ), Brazil.
| | | | | | | | | | | |
Collapse
|
12
|
Abstract
In the immediate posthatch period, chicks must transfer from metabolic dependence on yolk to utilization of exogenous feed. This study describes changes in intestinal luminal pancreatic enzyme activity and mucosal uptake posthatch as influenced by feed and Na intake. Chicks with access to feed increased in BW and small intestinal weight in the 48-h posthatch, whereas chicks without access to feed decreased in BW; however, small intestinal weight increased during this period. Chicks ingesting feed showed increases in total intestinal trypsin, amylase and lipase activities that were correlated with intestinal weights and BW. Chicks without access to feed showed little change in trypsin and amylase activities, and these increased only after feed consumption. Feeding a low-Na diet did not significantly change the regression coefficient between pancreatic enzyme activity and BW. Mucosal uptake was estimated by measuring Na+,K+-adenosine triphosphatase (ATPase) activity in small intestinal segments. In fed birds this activity increased in relationship to growth, whereas in nonfed birds uptake increased only after access to feed. Low-Na diets allowed only minimal mucosal uptake in all intestinal segments. This study indicates that secretion of trypsin and amylase into the intestine was triggered by feed intake. In addition, Na plays a critical role in intestinal uptake in the immediate posthatch period.
Collapse
Affiliation(s)
- D Sklan
- Faculty of Agriculture, Hebrew University, Rehovot, Israel.
| | | |
Collapse
|
13
|
Satyavathi C, Prabhakara Rao Y. Inhibition of Na+,K+-ATPase in Penaeus indicus postlarvae by lead. Comp Biochem Physiol C Toxicol Pharmacol 2000; 127:11-22. [PMID: 11081409 DOI: 10.1016/s0742-8413(00)00130-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The plasma membrane/mitochondrial fractions of Penaeus indicus postlarvae contain Mg2+-dependent ATPase, Na+,K+-stimulated ATPase, Na+-stimulated ATPase and K+-stimulated ATPase. The Na+,K+-activated, Mg2+-dependent ATPase was investigated further in relation to different pH and temperature conditions, and at various concentrations of protein, ouabain, ATP and ions in the incubation medium. In vitro and in vivo effects of lead were studied on the enzyme activity. In vitro lead inhibited the enzyme activity in a concentration-dependent manner with an IC50 value of 204.4 microM. In correlation with in vitro studies, in vivo investigations (both concentration and time dependent) of lead also indicated a gradual inhibition in enzyme activity. A maximum decrease of 85.3% was observed at LC50 (7.2 ppm) of lead for concentration-dependent experiments. In time-dependent studies, the decrease was maximal (81.7%) at 30 days of sublethal exposure (1.44 ppm). In addition, the substrate- and ion-dependent kinetics of Na+,K+-ATPase was studied in relation to in vitro exposure of lead; these studies suggest a non-competitive type of inhibition.
Collapse
Affiliation(s)
- C Satyavathi
- Division of Animal Physiology and Toxicology, Department of Zoology, Andhra University, Visakhapatnam, India.
| | | |
Collapse
|
14
|
Sklan D, Meir D, Noy Y. Chick small intestine brush border contains lipase and phospholipase activity. Br Poult Sci 1999; 40:392-6. [PMID: 10475638 DOI: 10.1080/00071669987502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
1. Uptake of triglycerides and phosphoglycerides was demonstrated in ligated washed chick intestinal segments in situ. Mucosal uptake was observed both in the jejunum and ileum of chicks and was not accompanied by significant luminal hydrolysis of acylglycerides. 2. Brush border membrane vesicles were prepared and lipase and phospholipase activities were demonstrated. These activities were enriched in parallel to the increase in activity of maltase and gamma-glutamyl transpeptidase in all small intestinal areas. 3. In order to determine if the pancreatic and brush border membrane lipolytic activities were similar different properties of these activities were examined. The relative activities of pancreatic and brush border membranes towards triolein and phosphatidylcholine differed. The pH-triolein activity curve and the use of different additives showed some diverging effects between the activities. These differences were not, however, sufficient to conclude that the brush border activity towards triolein is distinct from that of pancreatic lipase. 4. Lipolytic activity in the brush border may play a role in acylglyceride digestion, uptake and transport in the small intestine of the chick.
Collapse
Affiliation(s)
- D Sklan
- Faculty of Agriculture, Hebrew University, Rehovot, Israel
| | | | | |
Collapse
|
15
|
Camejo JL, Proverbio T, Proverbio F. Ouabain-insensitive, Na(+)-stimulated ATPase activity in rabbit cardiac sarcolemma. Comp Biochem Physiol B Biochem Mol Biol 1995; 110:345-8. [PMID: 7719642 DOI: 10.1016/0305-0491(94)00150-s] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The rabbit cardiac sarcolemma shows an ouabain, Na,K-stimulated ATPase activity and an ouabain-insensitive, Na-stimulated ATPase activity. The Na-ATPase has the following characteristics: (i) It is also stimulated by other monovalent cations. (ii) It is inhibited by 2 mM Furosemide and by 2 mM ethacrynic acid. (iii) It reaches maximal values (Vmax) at around 20 mM Na+. (iv) The apparent Km is around 5 mM. Except for the monovalent cation stimulation, the main characteristics of this ATPase are very similar to those of the ouabain-insensitive, Na-stimulated ATPase of mammalian kidneys.
Collapse
Affiliation(s)
- J L Camejo
- Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas
| | | | | |
Collapse
|
16
|
Calonge ML, Peral MJ, Ilundáin A. Intracellular pH regulation in cecal epithelial cells from the chick. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1153:213-8. [PMID: 8274490 DOI: 10.1016/0005-2736(93)90407-q] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Intracellular pH (pHi) regulation has been investigated in cells isolated from the proximal ceca of the chicken. pHi was measured with the pH-sensitive dye, 2',7'-bis(carboxyethyl)-5 (6)-carboxyfluorescein in nominally HCO(3-)-free solutions. Under resting conditions the pHi was 7.08. Removal of extracellular Na+ decreased pHi by approx. 0.24 pH units and the subsequent addition of Na+ increased pHi towards the control value. This Na(+)-dependent pHi recovery was inhibited by 5-(N-ethyl-N-isopropyl)amiloride (EIPA). Following an intracellular acidification, by abrupt withdrawal of NH4Cl, pHi alkalinized in the nominally absence of Na+. Rotenone, N-ethylmaleimide, N,N'-dicyclohexylcarbodiimide, 4-chloro-7-nitrobenz-2-oxa-1,3-diazole, iodoacetic acid and SCH 28080 inhibited the Na(+)-independent pHi recovery rate by 82, 82, 67, 74, 77 and 50% respectively. Bafilomycin A1 was without effect. Na(+)-independent cell alkalization was stimulated by external K+. In the presence of N-ethylmaleimide addition of Na+ induced a rapid pHi recovery. The initial rate of this recovery exhibited first-order dependence on Na+ concentration and it was inhibited by EIPA. The initial rate of Na(+)-dependent cell alkalization increased with a Hill coefficient greater than one when pHi was reduced from 7.2 to 6.2. The 'set point' for the exchanger is approx. 7.5. These studies demonstrate that in cecal epithelial cells exist at least two mechanisms for proton secretion: a Na(+)-H+ exchanger and a Na(+)-independent proton transport system.
Collapse
Affiliation(s)
- M L Calonge
- Departamento de Fisiología y Biología Animal, Facultad de Farmacia, Universidad de Sevilla, Spain
| | | | | |
Collapse
|
17
|
Ventrella V, Trombetti F, Pagliarani A, Trigari G, Pirini M, Borgatti AR. Salinity dependence of the ouabain-insensitive Mg2+-dependent Na+-ATPase in gills of rainbow trout (Oncorhynchus mykiss Walbaum) adapted to fresh and brackish water. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/0305-0491(92)90149-l] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
18
|
Chapter 2 Chemiosmotic systems and the basic principles of cell energetics. MOLECULAR MECHANISMS IN BIOENERGETICS 1992. [DOI: 10.1016/s0167-7306(08)60170-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
|
19
|
Schultz SG, Hudson RL. Biology Of Sodium‐Absorbing Epithelial Cells: Dawning of a New Era. Compr Physiol 1991. [DOI: 10.1002/cphy.cp060402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
20
|
Proverbio F, Marín R, Proverbio T. The ouabain-insensitive sodium pump. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. A, COMPARATIVE PHYSIOLOGY 1991; 99:279-83. [PMID: 1678327 DOI: 10.1016/0300-9629(91)90002-t] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- F Proverbio
- Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (I.V.I.C.), Caracas
| | | | | |
Collapse
|
21
|
Moretti R, Martín M, Proverbio T, Proverbio F, Marín R. Ouabain-insensitive Na-ATPase activity in homogenates from different animal tissues. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1991; 98:623-6. [PMID: 1831096 DOI: 10.1016/0305-0491(91)90265-f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
1. Two Na(+)-stimulated ATPase activities were determined in gill homogenates from squid, shrimp and teleost fish; in kidney slice homogenates from teleost fish, bullfrog, toad, iguana, chicken, duck, rat, pig and cow, as well as in homogenates from rat small intestinal cells, brain cortex and liver slices. The two Na(+)-stimulated ATPase activities, the Na- and the Na,K-ATPase, showed a different behavior toward K+ and ouabain. 2. The ouabain-insensitive, K(+)-independent, Na-ATPase activity for all the studied homogenates was completely inhibited by 2 mM furosemide. 3. An increase in cell volume of the kidney, brain cortex and liver slice preparations, as well as of the rat small intestinal cells, produced a concomitant increase of the ouabain-insensitive Na-ATPase.
Collapse
Affiliation(s)
- R Moretti
- Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (I.V.I.C.), Caracas, Venezuela
| | | | | | | | | |
Collapse
|
22
|
Abstract
In addition to the well-known (Na,K)-ATPase activity, an ouabain-insensitive Na-ATPase has been evidenced in the basolateral membrane of intestinal and renal cells from different mammals. Basolateral membranes of jejunal enterocytes from rats of different ages, i.e., very young, young, adult and old were separated by self-orienting, Percoll-gradient centrifugation. The total protein content and both Na- and (Na,K)-ATPase activities in initial homogenate and final pellets were analyzed. The dry weight of homogenate and pellet was also determined. The two ATPase activities and the protein content of the basolateral membrane fraction decrease with age when referred to the dry weight of the pellet. This diminution is also evident in the initial homogenate. The activation curve of Na-ATPase, hyperbolic in shape, gives Km and Vmax values unaffected by aging. The same behaviour is true for the kinetic parameters of (Na,K)-ATPase, which has a sigmoidal velocity curve. From these results, it seems that both Na- and (Na,K)-ATPase have the same characteristics in the basolateral membrane of the enterocyte throughout the life span of the animal, but they decrease quantitatively with aging.
Collapse
Affiliation(s)
- M Tosco
- Dipartimento di Fisiologia e Biochimica Generali, Universita' di Milano, Italy
| | | | | | | |
Collapse
|
23
|
Ventrella V, Trombetti F, Pagliarani A, Trigari G, Borgatti AR. Gill (Na+ + K+)- and Na+-stimulated Mg2+-dependent ATPase activities in the gilthead bream (Sparus auratus L.). COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1990; 95:95-105. [PMID: 2158872 DOI: 10.1016/0305-0491(90)90254-q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
1. Gilthead gill 10(-3) M ouabain-inhibited (Na+ + K+)-ATPase and 10(-2) M ouabain-insensitive Na+-ATPase require the optimal conditions of pH 7.0, 160 mM Na+, 20 mM K+, 5 mM MgATP and pH 4.8-5.2, 75 mM Na+, 2.5 mM Mg2+, 1.0 mM ATP, respectively. 2. The main distinctive features between the two activities are confirmed to be optimal pH, the ouabain-sensitivity and the monovalent cation requirement, Na+ plus another cationic species (K+, Rb+, Cs+, NH4+) in the (Na+ + K+)-ATPase and only one species (Na+, K+, Li+, Rb+, Cs+, NH4+ or choline+) in the Na+-ATPase. 3. The aspecific Na+-ATPase activation by monovalent cations, as well as by nucleotide triphosphates, opposed to the (Na+ + K+)-ATPase specificity for ATP and Na+, relates gilthead gill ATPases to lower organism ATPases and differentiates them from mammalian ones. 4. The discrimination between the two activities by the sensitivity to ethacrynic acid, vanadate, furosemide and Ca2+ only partially agrees with the literature. 5. Present findings are viewed on the basis of the ATPase's presumptive physiological role(s) and mutual relationship.
Collapse
Affiliation(s)
- V Ventrella
- Department of Biochemistry, Univeristy of Bologna, Italy
| | | | | | | | | |
Collapse
|
24
|
Proverbio T, Zanders I, Marín R, Rodríguez J, Proverbio F. Effects of Na+ and/or K+ on the Mg2+-dependent ATPase activities in shrimp (Macrobrachium amazonicum) gill homogenates. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/0305-0491(90)90296-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
25
|
Mg2+-dependent (Na+ + K+)- and Na+-ATPases in the kidneys of the gilthead bream (Sparus auratus L.). ACTA ACUST UNITED AC 1990. [DOI: 10.1016/0305-0491(90)90292-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
26
|
Chapter 6 The “Second” Sodium Pump and Cell Volume. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/s0070-2161(08)60010-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
27
|
Tosco M, Orsenigo MN, Esposito G, Faelli A. Ouabain-insensitive active sodium transport in rat jejunum: evidence from ATPase activities, Na uptake by basolateral membrane vesicles and in vitro transintestinal transport. Cell Biochem Funct 1988; 6:155-64. [PMID: 2970332 DOI: 10.1002/cbf.290060303] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The basolateral membrane of the jejunal enterocyte of the rat was separated by self-orienting Percoll-gradient centrifugation and further purified from brush border contamination. Pellets were analysed for Mg-, Na- and (Na,K)-ATPase activities. The uptake of 0.02 M NaCl was also followed by the rapid micro-filtration technique. Transintestinal transport of fluid and electrolytes, and cell water, Na and K were determined in the in vitro everted and incubated jejunum. There is ouabain-insensitive Na-ATPase in addition to the well-known (Na,K)-ATPase in the basolateral membrane. These are differently inhibited by furosemide and ethacrynate. Na uptake by osmotically active basolateral membrane vesicles is enhanced by ATP and a further enhancement is obtained if there is intravesicular K. The ATP effect is inhibited differently by strophanthidin, furosemide and ethacrynate. In the everted sac preparation, transintestinal transport of Na and fluid still occurs when the Na/K pump is totally inhibited by ouabain. These experimental results suggest that there is also a ouabain-insensitive Na pump, different from the Na/K pump, in the basolateral membrane.
Collapse
Affiliation(s)
- M Tosco
- Dipartimento di Fisiologia e Biochimica Generali, Università di Milano, Italy
| | | | | | | |
Collapse
|
28
|
Orsenigo MN, Tosco M, Esposito G, Faelli A. Ouabain-insensitive Na-ATPase activity in the basolateral membrane from rat jejunum. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1988; 20:1411-5. [PMID: 2977343 DOI: 10.1016/s0020-711x(98)90010-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
1. In the basolateral membrane preparation of the rat enterocyte (jejunal tract) there is not only the well-known (Na,K)-ATPase activity, but also a ouabain-insensitive Na-ATPase. 2. The Na-ATPase is not activated by anions or other monovalent cations. As a substrate, ATP cannot be replaced by other nucleotides. 3. The Na-ATPase is insensitive to ouabain and bumetanide, inhibited partially by furosemide and totally by ethacrynate. 4. The activation of Na-ATPase at different Na concentrations shows an hyperbolic curve (Km = 15.7 +/- 2.3 mM and Vmax = 204 +/- 19 nmoles Pi/mg protein per min) different from the sigmoidal curve (Km = 9.8 +/- 1.2 mM and Vmax = 640 +/- 15 nmoles Pi/mg protein per min) shown by (Na,K)-ATPase. 5. These results are compared with the corresponding ones found in other animals and tissues in which the Na-ATPase was found. 6. The Na-ATPase activity can be interpreted as the enzymatic correspondent of a ouabain-insensitive Na pump, present in the basolateral membrane of the enterocyte different in behaviour with respect to the known Na pump.
Collapse
Affiliation(s)
- M N Orsenigo
- Dipartimento di Fisiologia e Biochimica Generali, Universita' di Milano, Italy
| | | | | | | |
Collapse
|
29
|
Pagliarani A, Ventrella V, Trombetti F, Trigari G, Borgatti AR. (Na+ + K+)- and Na+-stimulated Mg2+-dependent ATPase activities in kidney of sea bass (Dicentrarchus labrax L.). COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1988; 90:41-52. [PMID: 2840241 DOI: 10.1016/0305-0491(88)90035-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
1. Sea bass kidney microsomal preparations contain two Mg2+ dependent ATPase activities: the ouabain-sensitive (Na+ + K+)-ATPase and an ouabain-insensitive Na+-ATPase, requiring different assay conditions. The (Na+ + K+)-ATPase under the optimal conditions of pH 7.0, 100 mM Na+, 25 mM K+, 10 mM Mg2+, 5 mM ATP exhibits an average specific activity (S.A.) of 59 mumol Pi/mg protein per hr whereas the Na+-ATPase under the conditions of pH 6.0, 40 mM Na+, 1.5 mM MgATP, 1 mM ouabain has a maximal S.A. of 13.9 mumol Pi/mg protein per hr. 2. The (Na+ + K+)-ATPase is specifically inhibited by ouabain and vanadate; the Na+-ATPase specifically by ethacrynic acid and preferentially by frusemide; both activities are similarly inhibited by Ca2+. 3. The (Na+ + K+)-ATPase is specific for ATP and Na+, whereas the Na+-ATPase hydrolyzes other substrates in the efficiency order ATP greater than GTP greater than CTP greater than UTP and can be activated also by K+, NH4+ or Li+. 4. Minor differences between the two activities lie in the affinity for Na+, Mg2+, ATP and in the thermosensitivity. 5. The comparison between the two activities and with what has been reported in the literature only partly agree with our findings. It tentatively suggests that on the one hand two separate enzymes exist which are related to Na+ transport and, on the other, a distinct modulation in vivo in different tissues.
Collapse
Affiliation(s)
- A Pagliarani
- Department of Biochemistry, Section of Veterinary Biochemistry, University of Bologna, Italy
| | | | | | | | | |
Collapse
|
30
|
Del Castillo JR, Whittembury G. Na+, K+ and Cl- transport in isolated small intestinal cells from guinea pig. Evidences for the existence of a second Na+ pump. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 901:209-16. [PMID: 3607047 DOI: 10.1016/0005-2736(87)90117-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Isolated small intestinal epithelial cells, after incubation at 4 degrees C for 30 min, reach ion concentrations (36 mM K+, 113 mM Na+ and 110 mM Cl-) very similar to those of the incubation medium. Upon rewarming to 37 degrees C, cells are able to extrude Na+, Cl- and water and to gain K+. Na+ extrusion is performed by two active mechanisms. The first mechanism, transporting Na+ by exchanging it for K+, is inhibited by ouabain and is insensitive to ethacrynic acid. It is the classical Na+ pump. The second mechanism transports Na+ with Cl- and water, is insensitive to ouabain but is inhibited by ethacrynic acid. Both mechanisms are inhibited by dinitrophenol and anoxia. The second Na+ extruding mechanism could be the Na+/K+/2Cl- cotransport system. However, this possibility can be ruled out because the force driving cotransport would work inwards, and because Na+ extrusion with water loss continues after substitution of Cl- by NO3-. We propose that enterocytes have a second Na+ pump, similar to that proposed in proximal tubular cells.
Collapse
|
31
|
Volume Maintenance in Isosmotic Conditions. ACTA ACUST UNITED AC 1987. [DOI: 10.1016/s0070-2161(08)60366-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
|
32
|
Bakeeva LE, Chumakov KM, Drachev AL, Metlina AL, Skulachev VP. The sodium cycle. III. Vibrio alginolyticus resembles Vibrio cholerae and some other vibriones by flagellar motor and ribosomal 5S-RNA structures. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 850:466-72. [PMID: 3730372 DOI: 10.1016/0005-2728(86)90115-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
An electron microscopic study of the basal bodies of the Vibrio albinolyticus flagellum revealed a four-disc structure. The diameters of the two discs localized closer to the cytoplasmic membrane proved to be about 2-fold shorter than those of the two others. In this respect the basal body of V. alginolyticus resembles very much that of V. cholerae described by Ferris and co-workers. The sequence of the V. alginolyticus ribosomal 5S-RNA showed that it is similar to those of V. cholerae, V. harveyi and some other vibriones. On the basis of the 5S-RNA sequences, a dendrogram of prokaryotes is presented. It confirmed the suggestion that V. alginolyticus is a typical representative of Vibrionaceae rather than a 'monster' greatly differing from other vibriones. Possible evolutionary relation of various bacterial species possessing the primary Na+ pumps is discussed.
Collapse
|
33
|
Dibrov PA, Lazarova RL, Skulachev VP, Verkhovskaya ML. The sodium cycle. II. Na+-coupled oxidative phosphorylation in Vibrio alginolyticus cells. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 850:458-65. [PMID: 2942186 DOI: 10.1016/0005-2728(86)90114-3] [Citation(s) in RCA: 72] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The role of Na+ in Vibrio alginolyticus oxidative phosphorylation has been studied. It has been found that the addition of a respiratory substrate, lactate, to bacterial cells exhausted in endogenous pools of substrates and ATP has a strong stimulating effect on oxygen consumption and ATP synthesis. Phosphorylation is found to be sensitive to anaerobiosis as well as to HQNO, an agent inhibiting the Na+-motive respiratory chain of V. alginolyticus. Na+ loaded cells incubated in a K+ or Li+ medium fail to synthesize ATP in response to lactate addition. The addition of Na+ at a concentration comparable to that inside the cell is shown to abolish the inhibiting effect of the high intracellular Na+ level. Neither lactate oxidation nor delta psi generation coupled with this oxidation is increased by external Na+ in the Na+-loaded cells. It is concluded that oxidative ATP synthesis in V. alginolyticus cells is inhibited by the artificially imposed reverse delta pNa, i.e., [Na+]in greater than [Na+]out. Oxidative phosphorylation is resistant to a protonophorous uncoupler (0.1 mM CCCP) in the K+-loaded cells incubated in a high Na+ medium, i.e., when delta pNa of the proper direction [( Na+]in less than [Na+]out) is present. The addition of monensin in the presence of CCCP completely arrests the ATP synthesis. Monensin without CCCP is ineffective. Oxidative phosphorylation in the same cells incubated in a high K+ medium (delta pNa is low) is decreased by CCCP even without monensin. Artificial formation of delta pNa by adding 0.25 M NaCl to the K+-loaded cells (Na+ pulse) results in a temporary increase in the ATP level which spontaneously decreases again within a few minutes. Na+ pulse-induced ATP synthesis is completely abolished by monensin and is resistant to CCCP, valinomycin and HQNO. 0.05 M NaCl increases the ATP level only slightly. Thus, V. alginolyticus cells at alkaline pH represent the first example of an oxidative phosphorylation system which uses Na+ instead of H+ as the coupling ion.
Collapse
|
34
|
Skulachev VP. Membrane-linked energy transductions. Bioenergetic functions of sodium: H+ is not unique as a coupling ion. EUROPEAN JOURNAL OF BIOCHEMISTRY 1985; 151:199-208. [PMID: 2863140 DOI: 10.1111/j.1432-1033.1985.tb09088.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The concept is developed according to which Na+, like H+, can play the role of a coupling ion in energy-transducing biomembranes. This idea is based on observations that (i) Na+ can be extruded from the cell by primary pumps (Na-motive NADH-quinone reductase, decarboxylase or ATPase), and (ii) the downhill Na+ flux into the cell can be coupled with the performance of all the three types of membrane-linked work i.e. chemical (ATP synthesis), osmotic (accumulation of solutes) and mechanical (motility). Marine alkalotolerant Vibrio alginolyticus represents the first example of such a complete sodium cycle pattern. Simplified versions of the sodium cycle or some of its constituents are found in the cytoplasmic membrane of a great variety of taxa including anaerobic, aerobic and photosynthetic bacteria, cyanobacteria and animals; this fact indicates that Na+ energetics should be regarded as a common case, rather than a rare exception applied to some natural niches only.
Collapse
|