scholarly journals Characterization of Na+ uptake in the endangered desert pupfish, Cyprinodon macularius (Baird and Girard)

2013 ◽  
Vol 1 (1) ◽  
pp. cot005-cot005 ◽  
Author(s):  
K. V. Brix ◽  
M. Grosell
Keyword(s):  
Desert Pupfish ◽  
Na Uptake ◽  
Cyprinodon Macularius

Characterization of Na(+)-H+ antiporter activity associated with human cheek epithelial cells

1994 ◽  
Vol 267 (1) ◽  
pp. C84-C93 ◽  
Author(s):  
E. J. McMurchie ◽  
S. L. Burnard ◽  
G. S. Patten ◽  
E. J. Lee ◽  
R. A. King ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Human Subjects ◽  
Maximum Velocity ◽  
Hill Coefficient ◽  
Transport Activity ◽  
Uptake Activity ◽  
Dimethyl Amiloride ◽  
Mouth Wash ◽  
Na Uptake

Na+ transport activity was characterized in human cheek epithelial cells obtained from normotensive adult subjects. The cells were isolated using a mouth-wash procedure and assayed for Na+ uptake using a radioactive (22Na+) rapid filtration assay. Cheek cells displayed proton-dependent Na+ uptake activity that was dependent on the magnitude of the externally directed proton gradient measured using the fluorescent probe 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein to determine intracellular pH. Amiloride, ethylisopropylamiloride (EIPA), 5-(N,N-dimethyl)-amiloride, 5-(N-methyl-N-isobutyl)-amiloride (MIA), and 5-(N,N-hexamethylene)-amiloride (NNHA) all inhibited proton-dependent Na+ uptake, with MIA, EIPA, and NNHA being the most potent. The Michaelis constant (Km) for extracellular Na+ was 5.7 mM, while the maximum velocity for Na(+)-H+ antiporter activity was 4.3 nmol Na+.mg protein-1.30s-1. The Km for intracellular H+ was 0.17 microM, with a Hill coefficient of 0.7. Stimulation by ouabain and inhibition by bumetanide of cheek cell proton-dependent Na+ uptake indicated only relatively low activities of Na(+)-K(+)-ATPase and Na(+)-K(+)-2Cl- cotransport, respectively. These results are consistent with the presence of Na(+)-H+ antiporter activity in cheek cells. Cheek cells therefore provide a convenient, relatively noninvasive source of tissue for examining Na(+)-H+ antiporter activity in human subjects.

Conservation Status of Desert Pupfish, Cyprinodon macularius, in México and Arizona

Copeia ◽  
1989 ◽  
Vol 1989 (2) ◽  
pp. 478 ◽  
Author(s):  
Dean A. Hendrickson ◽  
Alejandro Varela Romero
Keyword(s):  
Conservation Status ◽  
Desert Pupfish ◽  
Cyprinodon Macularius

Entire mitochondrion genome sequence of the Desert Pupfish, Cyprinodon macularius Baird & Girard, 1853

2014 ◽  
Vol 27 (6) ◽  
pp. 3893-3894
Author(s):  
Faustino Camarena-Rosales ◽  
Miguel A. Del Río-Portilla ◽  
Gorgonio Ruiz-Campos ◽  
Francisco J. García-De-León
Keyword(s):  
Genome Sequence ◽  
Desert Pupfish ◽  
Cyprinodon Macularius

Na+ Fluxes Across Isolated Perfused Gills of the Chinese Crab Eriocheir Sinensis

1981 ◽  
Vol 92 (1) ◽  
pp. 173-186 ◽  
Author(s):  
A. PEQUEUX ◽  
R. GILLES
Keyword(s):  
Ethacrynic Acid ◽  
Coupled System ◽  
Eriocheir Sinensis ◽  
Transport Processes ◽  
Functional Difference ◽  
Uptake System ◽  
Active Uptake ◽  
Branchial Epithelium ◽  
Na Uptake

Sodium transport processes in the branchial epithelium of euryhaline crustaceans have been investigated using a perfused preparation of gills isolated from Chinese crabs Eriocheir sinensis acclimated to dilute (FW) and to concentrated (SW) media. The results clearly establish the existence of a functional difference between the different pairs of branchiae with respect to their participation in the regulation of the blood Na+ content. In FW-acclimated animals, the Na+ active uptake which counter-balances the salt loss along the concentration gradient is mostly achieved across the three posterior pairs of gills. Conversely, the Na+ fluxes measured in the three anterior pairs are essentially passive and carrier-mediated. Further characterization of the Na+ uptake system present in the posterior gills by means of inhibitors like ouabain and ethacrynic acid indicates the existence of at least two spatially separated components of the Na+ carrying system. It is shown that NH4+ may be used as co-ion for Na+ but that such a coupling can only account for a very small part of the Na+ actively transported inward. The existence of an electrogenic mechanism or of another coupled system has thus to be postulated but remains at present a matter of speculation. To study FW-to-SW and SW-to-FW acclimation, Na+ fluxes were measured in isolated gills of SW-acclimated crabs and of FW crabs perfused and incubated in SW conditions. During acclimation to SW the Na+ active uptake in the posterior gills is abolished primarily as a result of inhibition of the Na+ carrier activity.

scholarly journals Bioaccumulation and toxicity of selenium during a life-cycle exposure with desert pupfish (Cyprinodon macularius)

2012 ◽  
Author(s):  
John M. Besser ◽  
William G. Brumbaugh ◽  
Diana M. Papoulias ◽  
Chris D. Ivey ◽  
James L. Kunz ◽  
...  
Keyword(s):  
Life Cycle ◽  
Desert Pupfish ◽  
Cyprinodon Macularius

Sodium transport in salamander proximal tubule at 5.5 degrees C

1991 ◽  
Vol 260 (3) ◽  
pp. F323-F330
Author(s):  
N. S. Morgunov ◽  
D. J. Hirsch
Keyword(s):  
Low Temperature ◽  
Basolateral Membrane ◽  
Maximal Activity ◽  
Membrane Resistance ◽  
Transepithelial Transport ◽  
Ambystoma Tigrinum ◽  
Intracellular Na Activity ◽  
Intracellular Milieu ◽  
Na Uptake

Na+ transport and electrophysiology of isolated perfused proximal tubules of the salamander Ambystoma tigrinum were compared at 22 and 5.5 degrees C, a range over which these animals normally live. Both intracellular Na+ activity and basolateral membrane potential were unaffected by temperature, whereas transepithelial potential depolarized from -6.5 +/- 0.8 mV at 22 degrees C to -3.5 +/- 0.6 mV at 5.5 degrees C (P less than 0.05). Compared with 22 degrees C, reduction of temperature to 5.5 degrees C included major increases in apical membrane resistance (2,052 +/- 473 omega.cm2 to 18,464 +/- 2,667 omega.cm2) and basolateral membrane resistance (491 +/- 113 omega.cm2 to 1,780 +/- 256 omega.cm2) (P less than 0.01). Sequential increases of luminal glucose concentration allowed characterization of the Na(+) -glucose cotransporter at both temperatures. The Km was stable (2 mM), but the maximal activity (Vmax) at 5.5 degrees C of 167 peq/5 cm2 increased to 1,000 peq/5 cm2 at 22 degrees C (P less than 0.05). In parallel with this temperature sensitivity of apical Na+ entry, basolateral Na+ pump activity was reduced at low temperature. Rubidium uptake at 22 degrees C was reduced by 40% at 5.5 degrees C. The rate of decrease of intracellular Na+ activity when tubules were perfused with substrate-free solution was -2.6 +/- 0.7 mM/min at 5.5 degrees C, compared with -4.9 +/- 1.2 mM/min at 22 degrees C. We conclude that low temperature reduces both Na+ uptake and efflux, allowing stability of intracellular milieu despite reduction in net transepithelial transport.

Localization and functional characterization of Na+/H+ exchanger isoform NHE4 in rat thick ascending limbs

2001 ◽  
Vol 281 (4) ◽  
pp. F707-F717 ◽  
Author(s):  
Régine Chambrey ◽  
Patricia L. St. John ◽  
Dominique Eladari ◽  
Fabienne Quentin ◽  
David G. Warnock ◽  
...  
Keyword(s):  
Rat Kidney ◽  
Basolateral Membrane ◽  
Functional Characterization ◽  
Membrane Vesicles ◽  
Affinity Constant ◽  
Thick Ascending Limb ◽  
Collecting Ducts ◽  
Inhibition Curve ◽  
Na Uptake

The Na+/H+ exchanger NHE4 was cloned from a rat stomach cDNA library and shown to be expressed predominantly in the stomach and less dramatically in the kidney. The role and precise localization of NHE4 in the kidney are still unknown. A polyclonal antibody against a unique NHE4 decapeptide was used for immunohistochemistry in rat kidney. Simultaneous use of antibodies to Tamm-Horsfall glycoprotein and aquaporin-2 or -3 permitted identification of thick ascending limbs and collecting ducts, respectively. The results indicate that NHE4 is highly expressed in basolateral membranes of thick ascending limb and distal convoluted tubule, whereas collecting ducts from cortex to inner medulla and proximal tubules showed weaker basolateral NHE4 expression. Western blot analysis of NHE4 in membrane fractions prepared from the inner stripe of the outer medulla revealed the presence of a 95-kDa protein that was enriched in basolateral membrane vesicles isolated from medullary thick ascending limbs. The inhibition curve of H+-activated 22Na uptake by 5-( N-ethyl- N-isopropyl)amiloride (EIPA) was consistent with the presence, beyond the EIPA high-affinity NHE1 isoform, of an EIPA low-affinity NHE with apparent half-maximal inhibition of 2.5 μM. Kinetic analyses showed that the extracellular Na+ dependence of NHE4 activity followed a simple hyperbolic relationship, with an apparent affinity constant of 12 mM. Intravesicular H+ activated NHE4 by a positive cooperative mechanism. NHE4 had an unusual low affinity for intravesicular H+ with a half-maximal activation value of p K6.21. We conclude that NHE4, like NHE1, is expressed on the basolateral membrane of multiple nephron segments. Nevertheless, these two proteins exhibited dramatically different affinities for intracellular H+, suggesting that they may play distinct physiological roles in the kidney.

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