| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
a Renal Unit and Program in Membrane Biology, Massachusetts General Hospital,
b Department of Pathology, Harvard Medical School, Charlestown, Massachusetts 02129
c Renal Division, Brigham and Women's Hospital, Boston, Massachusetts 02115
d Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06520
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Despite its potential importance in male reproductive physiology, relatively few studies have examined the mechanism of luminal fluid acidification and pH regulation in this organ. Early work showing the Na+ dependence of an acidic luminal pH implicated an apical Na/H- exchanger in this process [1]. Our recent studies have demonstrated that a bafilomycin-sensitive H+ATPase is responsible for a large fraction of the proton secretion measured in the vas deferens [10]. The apical H+ATPase that is involved in this process is selectively located in specialized cells of the epithelium that line the epididymis and the vas deferens [10, 11]. In the caput epididymidis, these cells are the so-called apical and/or narrow (hereafter referred to as apical/narrow) cells, while in the corpus and cauda the H+ATPase is exclusively found in the clear cells. These cells also contain high levels of the cytosolic isoform of carbonic anhydrase, CAII [10, 12, 13].
The involvement of bicarbonate in epididymal proton secretion is suggested by studies demonstrating that the CAII inhibitor acetazolamide increases luminal pH in the cauda epididymidis [1]. Our recent studies have also shown a similar inhibitory effect of acetazolamide on proton secretion in the vas deferens [14]. However, an in vivo study failed to demonstrate any effect of systemic acetazolamide administration on luminal pH in the caput and corpus epididymidis [7]. In the kidney, basolateral bicarbonate extrusion is mediated by the basolateral chloride-bicarbonate exchanger (anion exchanger) AE1 in intercalated cells [15] and by a basolateral Na+/HCO3- cotransporter in the proximal tubule [16, 17]. Our functional studies on acidification in the vas deferens have demonstrated that H+ secretion is inhibited by 4-acetamido-4'-isothiocyanato-stilbene-2,2'-disulfonic acid (SITS), an inhibitor of HCO3- transporters, but is Cl- independent [14]. These data are not consistent with the involvement of a Cl-/HCO3- exchanger in this process but instead suggest that an Na+/HCO3- cotransporter may participate in luminal acidification.
On the basis of these considerations, we took advantage of the recent cloning of an Na+/HCO3- cotransporter (NBC) from salamander and rat kidney [18, 19], and we used an anti-rat NBC antibody [20] to perform immunolocalization of the NBC in rat excurrent ducts. In parallel, we localized NBC mRNA by in situ hybridization in the epididymis. Our results show that this protein is expressed in the epididymis, that it is basolaterally located in principal cells and H+ATPase-rich cells, and that the highest level of expression is in the proximal parts of the epididymis.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
A rabbit polyclonal antibody against the cloned rat kidney Na+/HCO3- cotransporter protein (rkNBC) was made using a fusion protein (MBP-NBC-5) that consisted of maltose-binding protein (MBP) coupled to amino acids 928-1035 of rkNBC, corresponding to the C-terminus of the protein [20]. For immunofluorescence microscopy, goat anti-rabbit IgG coupled to CY3 was used (Sigma Chemical Co., St. Louis, MO); for Western blotting, horseradish peroxidase-conjugated goat anti-rabbit IgG was used (Jackson Immunoresearch, West Grove, PA).
Immunofluorescence Microscopy
Sexually mature (10 wk old, 300 g) male Sprague-Dawley rats were anesthetized with Nembutal (0.5 ml i.p.; Abbott Laboratories, North Chicago, IL) and perfused via the left ventricle with PBS (0.9% NaCl in 10 mM sodium phosphate buffer, pH 7.4) followed by a fixative [21] containing 4% paraformaldehyde, 10 mM sodium periodate, 10 mM lysine, and 5% sucrose in 0.1 M sodium phosphate buffer (PLP), as described previously [10, 11]. Epididymis and vas deferens were cryoprotected in 30% sucrose/PBS, mounted for cryosectioning in Tissue-Tek (Miles, Inc., Elkhart, IN), and quick-frozen in liquid nitrogen. Sections were cut at 4 µm using a Reichert (Reichert Jung, Nossloch, Germany) Frigocut cryostat and picked up onto Superfrost/Plus microscope slides (Fisher Scientific, Pittsburgh, PA). For indirect immunofluorescence microscopy, sections were hydrated 5 min in PBS and treated for 4 min with SDS (1% in distilled water)—an antigen retrieval technique that we have previously described [22]. Sections were washed in PBS two times for 5 min each time and then blocked in a solution of 1% BSA/PBS/sodium azide for 15 min. Primary antibodies, diluted to 1:50 or 1:100 in PBS, were applied in a moist chamber for either 1.5 h at room temperature or overnight at 4°C. Preimmune and immune sera were used at the same dilution. In competition experiments, specific (MBP-NBC-5) or irrelevant peptides (MBP coupled to the alpha fragment of beta-galactosidase) were mixed with primary antibody at 20 µg/ml and allowed to incubate for at least 1 h at room temperature prior to use. Sections were washed twice in PBS containing 2.7% NaCl to reduce background staining and once in normal PBS. Secondary antibody was then applied (2.5 µg/ml) for 1 h at room temperature followed by washes as above. Slides were mounted in a 2:1 mixture of Vectashield (Vector Laboratories, Burlingame, CA) mounting medium/1.5 M Tris solution (pH 8.9). Inspection and photography were performed on a Nikon (Garden City, NY) FXA epifluorescence microscope using Kodak (Eastman Kodak, Rochester, NY) TMAX 400 film push-processed to 1600 ASA. When the results of fusion protein competition experiments were to be compared, photos were taken at fixed exposure times and printed under identical conditions.
Conventional Electron Microscopy
Epididymis was fixed in 2.5% glutaraldehyde in 0.1 M phosphate buffer, pH 7.4, and was divided into initial segment, caput, body, and cauda. Tissue was chopped into smaller pieces and immersed in the same fixative, as described previously [23]. Material was postfixed in OsO4, stained en bloc with uranyl acetate, dehydrated in ethanol, and embedded in Epon (Electron Microscopy Sciences, Ft. Washington, PA). Thin sections were stained with uranyl acetate and lead citrate.
Immunoperoxidase Electron Microscopy
PLP-fixed epididymis was cryoprotected for 1 h in 10% dimethyl sulfoxide in PBS. After freezing in liquid nitrogen, 50-µm frozen sections were cut and transferred into PBS. Sections were incubated for 10 min in 0.1% SDS in PBS, then washed for a total of 1 h in PBS. Sections were permeabilized for 1 h in PBS containing 1% BSA, 0.2% gelatin, and 0.05% saponin. This solution was also used to dilute primary antibody and as a rinse solution between antibody incubation steps. Sections were incubated overnight at 4°C in primary antibody diluted 1:100 and were washed six times, 5 min each in rinse solution. Goat anti-mouse IgG coupled to biotin (Vector; 1:100 dilution) was applied for 6 h at room temperature, and sections were washed as above. ABC (avidin-biotin-peroxidase) reagent (Vector) was prepared according to the manufacturer's instructions and applied overnight; this was followed by washes and fixation for 30 min at room temperature in 1% glutaraldehyde in PBS containing 5% sucrose. Sections were rinsed five times, 5 min each in 0.05 M Tris, pH 7.6, containing 7.5% sucrose. Enzymatic activity was detected by a 10-min incubation in diaminobenzidine/H2O2. Sections were washed in Tris/sucrose three times for 5 min each to stop the reaction and then washed for 5 min in 0.1 M sodium cacodylate buffer, pH 7.4. Sections were postfixed for 1 h in 1% OsO4 in cacodylate buffer, stained en bloc for 1 h with 2% aqueous uranyl acetate, rinsed in distilled water, and dehydrated and embedded in Epon for electron microscopy. Thin sections were examined using a Philips (Eindhoven, The Netherlands) CM10 electron microscope.
Western Blotting
Rats were perfused through the left ventricle with ice-cold PBS (pH 7.4) containing 1 tablet of Complete Protease Inhibitor per 50 ml (Boehringer Mannheim GmbH, Mannheim, Germany). Tissue samples were removed, cut into smaller pieces with a razor blade, washed in ice-cold PBS to remove sperm, transferred to 1 ml of ice-cold lysis buffer containing protease inhibitors, and homogenized using a small Dounce tissue grinder (Wheaton, Millville, NJ) and a 27-gauge needle/syringe. Lysis buffer consisted of 15 mM NaCl, 10 mM Tris (pH 7.4), 1% Triton X-100, 0.5% Igepal (Sigma), 1 mM EDTA, 1 mM EGTA (pH 7.4), 200 µM PMSF, and 1/4 tablet of Complete Protease Inhibitor Cocktail per 10 ml of the buffer solution. Sperm were collected from cauda epididymidis by cutting the tissue open and washing briefly in PBS with protease inhibitors. The sperm sample was then centrifuged (2 min at 14 000 rpm), and the pellet (enriched in sperm) was resuspended in 1 ml of lysis buffer and homogenized as for other tissues. Homogenates were diluted 3:1 in 4-strength Laemmli (reducing) sample buffer (Boston BioProducts, Ashland, MA), boiled for 5 min, and centrifuged (2 min, 14 000 rpm). Sperm supernatant was loaded at 40 µg protein per lane onto SDS-polyacrylamide (8%) mini-gels and separated using the Laemmli method [24]. The pellet fraction of the caput epididymidis was resuspended in 100 µl Laemmli sample buffer, boiled for 10 min, vortexed, and reboiled for 5 min. The resuspended pellet fraction was centrifuged for 20 sec, and 30 µl of this supernatant was loaded on the gel. Proteins were transferred in a Bio-Rad (Richmond, CA) semi-dry transfer cell onto Immobilon-P transfer membrane (Millipore Corp., Bedford, MA). The quality of transfer was checked by protein staining using Coomassie brilliant blue. After destaining, membranes were blocked overnight at 4°C in 5% normal goat serum in Blotto (5% nonfat dry milk/0.05% Tween 20/PBS). Antibody incubations were done in Blotto at room temperature. Primary antibody (NBC-5) and preimmune serum were diluted 1:5000, and secondary antibody was diluted 1:10 000. For peptide competition, whole immune serum was mixed with relevant (NBC-5) or irrelevant (MBP) peptides at 1 µg/µl and incubated 1 h at room temperature as for immunofluorescence. Washes between and after incubations were done in Blotto and repeated four times, 10 min each. Detection of antibody binding was performed with the Enhanced ChemiLuminescence (ECL+Plus) method (Amersham Life Sciences, Buckinghamshire, UK) using Kodak X-Omat Blue XB-1 film.
In Situ Hybridization
Digoxigenin-labeled antisense and sense run-off transcripts were synthesized using a Genius Kit (Boehringer Mannheim) from a PCR fragment, which was flanked by promoter sites for SP6 and T7 polymerase. The fragment contained nucleotides 2234-3495 of the rkNBC sequence corresponding to the carboxyterminus region plus 3'-untranslated region. Transcripts were alkali-hydrolyzed to an average length of 200-400 nucleotides. In situ hybridization was performed on cryosections (10 µm) of fresh-frozen tissue as described previously [25]. The hybridization buffer consisted of 50% formamide, 5-strength SSC (single-strength SSC is 0.15 M sodium chloride and 0.015 M sodium citrate), 2% blocking reagent (Boehringer Mannheim), 0.02% SDS, and 0.1% N-laurylsarcosine. Probe concentrations were ~200 ng/ml. Sections were immersed in slide mailers in hybridization solution and hybridized at 68°C for 3 days. Sections were then washed three times in double-strength SSC and two times, 30 min each, in 0.2-strength SSC at 68°C. The hybridized labeled probes were visualized using anti-digoxigenin Fab fragments (Boehringer Mannheim) and 5-bromo-4-chloro-3-indolyl-phosphate, toluidine-salt/nitro blue tetrazolium chloride substrate [25]. Sections were developed in substrate solution for 44 h; they were then rinsed in 100 mM Tris, 100 mM NaCl, 1 mM EDTA at pH 9.5 and coverslipped with Vectashield (Vector).
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
As shown in Figure 1 (lane 2), Western blotting of the epididymis with the anti-NBC antibody revealed a single band at about 160 kDa. This band was almost completely abolished when the antibody was preabsorbed with the immunizing peptide (Fig. 1, lane 4), and neither preimmune serum nor secondary antibody alone revealed any protein bands (not shown). In preliminary experiments, we found that the protein recognized by the antibody was highly susceptible to proteolytic degradation, and it was necessary to isolate tissue from rats perfused in situ with ice-cold buffer containing protease inhibitors. In addition, storage of isolated tissue samples above -80°C also resulted in partial degradation of the 160-kDa band and in the appearance of a band at approximately 60 kDa. The predicted molecular size of rNBC is 116 kDa [19]; and when expressed in Xenopus oocytes, this antibody detects a 130-kDa band [20, 26]. We attribute the higher molecular weight band in epididymis to differential posttranslational processing, probably increased glycosylation, which is known to be cell type-specific [27, 28] and which is indicated, in our study, by the detection of material staining above the NBC band.
|
An additional consideration was the presence of an NBC-reactive protein in spermatozoa harvested from the cauda epididymidis. The presence of NBC in sperm is shown in lane 1 of Figure 1, and sperm were also positive by immunocytochemistry in some regions of the epididymis (Fig. 2B). Because of this, sperm were removed from all samples of epididymis used for Western blotting by washing the cut-open tubules in cold buffer prior to solubilization in sample buffer.
|
Immunofluorescence
Indirect immunofluorescence staining of the epididymis for NBC was dependent upon pretreatment of the tissue sections with SDS, an antigen-retrieval technique [22], prior to application of the primary antibody. The anti-NBC antibody produced a strong basolateral staining in epithelial cells in the initial segment (Fig. 3A) and in tubules of the intermediate zone (see [29] for nomenclature) of the epididymis (Fig. 2A). The staining became progressively weaker in the larger tubules of the caput (Fig. 2B), corpus, cauda, and vas deferens, although faint and specific basolateral staining was observed in all of these more distal regions. In some tubule segments, a relatively weak apical staining was seen (Fig. 3, A and B); but this staining was also found after incubation of the sections with preimmune serum (data not shown) or after preincubation of the primary antibody with the specific immunizing peptide (Fig. 3C) and represents, therefore, nonspecific staining. Basolateral staining was not observed when preimmune serum replaced the immune serum, and the staining was greatly diminished by preincubating the primary antibody with the specific immunizing peptide (Fig. 3C), but not when an MBP peptide was used (Fig. 3B). Blood vessels were also labeled (Figs. 2A and 3, A and B), and no staining of the efferent ducts was seen with the anti-NBC-5 antibody (data not shown).
|
Electron Microscopy
By conventional light and electron microscopy, apical/narrow cells have several morphological characteristics distinct from those of principal cells, including a dark cytoplasm, many mitochondria, numerous vesicles beneath the apical plasma membrane, and an oval nucleus located in the mid to apical part of their cytoplasm [23, 30]. Figure 4A shows a transverse section through the mid-to-apical region of the epithelium of the initial segment that includes one apical/narrow cell and several principal cells. The apical/narrow cell is identified by its characteristic angular profile and by the presence of a nucleus, which is located toward the cell apex in these cells. Principal cells are identified by their larger size, dilated cisternae of endoplasmic reticulum and Golgi, and the absence of the nucleus in this plane of sectioning [23]. By immunoelectron microscopy, the NBC protein was located on the basolateral plasma membrane of both principal and apical/narrow cells in a similar region of the epididymis (Fig. 4B).
|
In Situ Hybridization
NBC message was detected in epithelial cells of the epididymis using the antisense probe developed from a nucleotide sequence corresponding to the C-terminus region of the protein. It was extremely strong in the initial segment (Fig. 5A), intermediate zone, and caput epididymidis and became progressively weaker toward the cauda (Fig. 5B). This message distribution paralleled the localization pattern of the NBC protein in these cells. Sections incubated with the sense probe showed only a low level of background staining (Fig. 5C). No cellular heterogeneity in message expression was detectable at the level of resolution afforded by this technique, in agreement with the presence of the NBC protein in all epithelial cells.
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
The involvement of basolateral bicarbonate transport in this apical acidification process is suggested by three lines of evidence: 1) the HCO3- concentration of the luminal fluid in the epididymis is reduced to < 15% of the level in blood, indicating that active HCO3- reabsorption occurs in this tissue [4]; 2) carbonic anhydrase type II (CAII) is concentrated in the H+ATPase-rich cells of the epididymis and vas deferens, and acetazolamide, a carbonic anhydrase inhibitor, blocks acidification in the vas deferens and in the cauda epididymidis [1, 14]; 3) our recent data show that SITS, a blocker of HCO3--transporting proteins, inhibits proton secretion in the vas deferens in a chloride-independent fashion [14].
Basolateral HCO3 extrusion in epithelial cells can be mediated by a Cl-/HCO3- anion exchanger such as AE1, as seen in specialized proton-secreting intercalated cells in the kidney [15]; or alternatively it can be achieved by the activity of a basolateral Na+-HCO3- cotransporter, similar to that present in renal proximal tubules [17, 31, 32]. Our present results show that an Na+-HCO3- cotransporter is located in the basolateral plasma membrane of epithelial cells of the epididymis and the vas deferens, where it is poised to play a role in the regulation of luminal pH in the excurrent duct system. However, the expression of this protein, as well as the respective mRNA, was considerably greater in the proximal regions of the epididymis, where H+ATPase-rich cells are less abundant, than in the cauda and the vas deferens. This result suggests that proton secretion and bicarbonate transport may be regulated in different ways and may involve different sets of transport proteins in various regions of the excurrent duct system—bicarbonate reabsorption being predominant in the initial segment and intermediate zone, and active proton secretion occurring mainly in the cauda epididymidis. The high levels of the NBC protein in the initial segment and intermediate zone correlate with the very low concentration of HCO3- that is reached when the luminal fluid enters the proximal caput [2].
Also of interest is the abundance of the NBC protein both in principal cells and in apical/narrow cells that extrude protons via an apical H+ATPase. It is possible that the Na+-HCO3- cotransporter has a different role in these two distinct cell types. The apical/narrow cells are greatly enriched in the cytoplasmic isoform of carbonic anhydrase, CAII, compared to what is seen in adjacent principal cells, indicating that they play a more active role in transepithelial acid-base movement than the principal cells [10, 12, 13], although both cell types in some regions of the epididymis contain apical CAIV [13]. In this respect, it is interesting that one previous study failed to demonstrate an effect of CAII inhibition on acidification in the more proximal portions of the epididymis [7]. This may be explained by the fact that the source of HCO3- in the proximal epididymis is from the HCO3--rich luminal fluid that originates from the seminiferous tubules, whereas in more distal regions, CAII plays a greater role in generating H+ and HCO3- that are transported apically and basolaterally, respectively, by polarized transporters in epithelial cells. The Na+-HCO3- cotransporter might, therefore, contribute to transepithelial proton and bicarbonate transport in apical/narrow cells and to significant bicarbonate reabsorption in principal cells.
A second role for the NBC protein might be an involvement in intracellular pH homeostasis in principal cells. As mentioned above, our recent studies have shown that luminal proton secretion in the vas deferens involves a chloride-independent, SITS-sensitive bicarbonate transporter [14], indicating the possible role of an Na+-HCO3- cotransporter. Further studies will be required to reveal the potential involvement of this cotransporter in intracellular pH regulation and/or net transepithelial acid-base transport in different cell types of the epididymis and vas deferens.
Bicarbonate is involved in the regulation of spermatozoa function. This anion plays a key role in triggering modification of the architecture of the sperm plasma membrane during capacitation, a process that allows spermatozoa to interact with and fertilize the egg [33, 34]. Capacitation is a series of positive destabilizing events that eventually lead to sperm death [33]. Therefore, initiation of premature capacitation in vivo would represent a threat for sperm survival during storage in the epididymis. The establishment of a low HCO3- concentration in the lumen of the epididymis [2, 35] might thus contribute to maintaining an optimum environment for proper sperm storage and viability. Such a low bicarbonate concentration is probably even more important as sperm acquire detectable levels of the NBC protein during their transit through the epididymis and themselves possess bicarbonate transport mechanisms.
The antibody used in this study was raised against an rkNBC C-terminal peptide and might not recognize all isoforms of NBC. The lower reactivity of this antibody in more distal regions of the epididymis, and its lack of reactivity with the efferent ducts, could reflect a low level of this NBC isoform in these regions; but this result does not rule out the presence of distinct NBC transporter(s) isoforms that are not detected by this antibody in these segments.
In summary, our present data show that an Na+/HCO3- cotransporter is present in the basolateral plasma membrane of cells lining parts of the excurrent ducts of the rat. This protein may be involved in transepithelial acid-base transport, and in addition it may have a role in regulation of intracellular pH.
|
FOOTNOTES |
|---|
2 Correspondence: Sylvie Breton, Renal Unit and Program in Membrane Biology, Massachusetts General Hospital East, 149 13th Street, Charlestown, MA 02129. FAX: 617 726 5669; sbreton{at}receptor.mgh.harvard.edu
3 Current address: Zoophysiological Laboratory, August Krogh Institute, 13 Universitetsparken, DK-2100, Kbh. O, Denmark.
Accepted: October 6, 1998.
Received: September 1, 1998.
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
This article has been cited by other articles:
|
|
 |
|
  A. Pushkin and I. Kurtz SLC4 base (HCO3-, CO32-) transporters: classification, function, structure, genetic diseases, and knockout models Am J Physiol Renal Physiol, March 1, 2006; 290(3): F580 - F599. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Pastor-Soler, C. Pietrement, and S. Breton Role of Acid/Base Transporters in the Male Reproductive Tract and Potential Consequences of Their Malfunction Physiology, December 1, 2005; 20(6): 417 - 428. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Hermo, D. L. Chong, P. Moffatt, W. S. Sly, A. Waheed, and C. E. Smith Region- and Cell-specific Differences in the Distribution of Carbonic Anhydrases II, III, XII, and XIV in the Adult Rat Epididymis J. Histochem. Cytochem., June 1, 2005; 53(6): 699 - 713. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Abuladze, A. Pushkin, S. Tatishchev, D. Newman, P. Sassani, and I. Kurtz Expression and localization of rat NBC4c in liver and renal uroepithelium Am J Physiol Cell Physiol, September 1, 2004; 287(3): C781 - C789. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. Choi, L. Hu, J. D. Rojas, B. M. Schmitt, and W. F. Boron Role of glycosylation in the renal electrogenic Na+-HCO-3 cotransporter (NBCe1) Am J Physiol Renal Physiol, June 1, 2003; 284(6): F1199 - F1206. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. W. Carlin, J. H. Lee, D. C. Marcus, and B. D. Schultz Adenosine Stimulates Anion Secretion Across Cultured and Native Adult Human Vas Deferens Epithelia Biol Reprod, March 1, 2003; 68(3): 1027 - 1034. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. A. Demarco, F. Espinosa, J. Edwards, J. Sosnik, J. L. de la Vega-Beltran, J. W. Hockensmith, G. S. Kopf, A. Darszon, and P. E. Visconti Involvement of a Na+/HCO-3 Cotransporter in Mouse Sperm Capacitation J. Biol. Chem., February 21, 2003; 278(9): 7001 - 7009. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Gross and I. Kurtz Structural determinants and significance of regulation of electrogenic Na+-HCO3- cotransporter stoichiometry Am J Physiol Renal Physiol, November 1, 2002; 283(5): F876 - F887. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. W. Carlin, R. R. Quesnell, L. Zheng, K. E. Mitchell, and B. D. Schultz Functional and molecular evidence for Na+-HCO3- cotransporter in porcine vas deferens epithelia Am J Physiol Cell Physiol, October 1, 2002; 283(4): C1033 - C1044. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. L. Phillips and B. D. Schultz Steroids Modulate Transepithelial Resistance and Na+ Absorption Across Cultured Porcine Vas Deferens Epithelia Biol Reprod, April 1, 2002; 66(4): 1016 - 1023. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. L. Sedlacek, R. W. Carlin, A. K. Singh, and B. D. Schultz Neurotransmitter-stimulated ion transport by cultured porcine vas deferens epithelium Am J Physiol Renal Physiol, September 1, 2001; 281(3): F557 - F570. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Karhumaa, K. Kaunisto, S. Parkkila, A. Waheed, S. Pastorekova, J. Pastorek, W. S. Sly, and H. Rajaniemi Expression of the transmembrane carbonic anhydrases, CA IX and CA XII, in the human male excurrent ducts Mol. Hum. Reprod., July 1, 2001; 7(7): 611 - 616. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Bagnis, M. Marsolais, D. Biemesderfer, R. Laprade, and S. Breton Na+/H+-exchange activity and immunolocalization of NHE3 in rat epididymis Am J Physiol Renal Physiol, March 1, 2001; 280(3): F426 - F436. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D Brown and S Breton H(+)V-ATPase-dependent luminal acidification in the kidney collecting duct and the epididymis/vas deferens: vesicle recycling and transcytotic pathways J. Exp. Biol., January 1, 2000; 203(1): 137 - 145. [Abstract]
|
|
|
|
|
|
L. J. Jensen, A. K. Stuart-Tilley, L. L. Peters, S. E. Lux, S. L. Alper, and S. Breton Immunolocalization of AE2 Anion Exchanger in Rat and Mouse Epididymis Biol Reprod, October 1, 1999; 61(4): 973 - 980. [Abstract] [Full Text]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
