Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Regional differences in the proximal part of mouse epididymis were reported to provide a morphological baseline for studies on functional zonation of this part that is critical in sperm maturation. Macroscopical, histological, ultrastructural, and histochemical observations permitted us to subdivide this part into five segments, characterized by epithelial height, nuclear position, cytological and histochemical features of principal cells. Segment I corresponded to the initial segment previously described in rodents. Segment II differed from segment I by endoplasmic reticulum (ER) and dictyosomes aspect in principal cells, apical alkaline phosphatase and Ca2+-dependent ATPase activities. Segment III was characterized by spermatozoa package, high content of cells in multivesicular bodies, mitochondria shape, complex interdigitating membranes, and strong periodic acid-Schiff (PAS)-positive cell border. Segments IV and V presented the same cytological features but differed by their esterase activity. In the principal cells of each segment, dense spherical concretions were scattered in ER caveolae. Cells with apical nuclei were classified into two groups. The cells of the first group presented the same morphological and histochemical features as the adjacent principal cells and were scattered in the five segments ("apical cells"). The cells of the second group differed from the others by their goblet shape, a dense cytoplasm, and a high mitochondria succinate-D activity. They presented different cytological and histochemical features depending on their localization in segments I ("narrow cells"), II ("prominent cells"), or III, IV, V ("mitochondria goblet-cells"). The possible relationships between epithelium structure and epididymal functions were herein discussed.
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PMID:Regional differences of the proximal part of mouse epididymis: morphological and histochemical characterization. 646 30

A study was carried out to investigate the short-circuit current (Isc) response to noradrenaline (NA) and the signal transduction mechanisms involved in cultured rat cauda epididymal epithelium. In normal Krebs-Henseleit solution, NA (10 mumol.l-1) added basolaterally elicited a biphasic Isc response consisting of a transient spike followed by a second sustained response. The biphasic response was almost abolished by removing ambient Cl-. Preloading the tissues with a cell-permeant Ca2+ chelator, 1,2-bis(2-aminophenoxy) ethane-N,N,N',N',-tetraacetic acid acetoxymethyl ester (BAPTA/AM), or pretreating them with thapsigargin (Tg), a microsomal adenosine triphosphatase inhibitor abolished the initial spike in the Isc response to NA, but had little effect on the second component. Pretreating the tissues with a non-selective beta-antagonist, nadolol, reduced the second Isc response in a dose-dependent fashion but the initial spike was not affected. Microfluorimetric studies showed that NA (100 mumol.l-1) elicited single Ca2+ spikes in isolated epididymal cells, which could be abolished by prior treatment with Tg. Biochemical assays showed that NA (10 mumol.l-1) increased intracellular cyclic adenosine monophosphate concentration ([cAMP]i) and the response was abolished by prior treatment with nadolol (50 mumol.l-1). The results showed that NA elicited a biphasic Isc response mediated by a rise in intracellular Ca2+ concentration ([Ca2+]i) followed by a rise in [cAMP]i. The Ca(2+)-mediated Isc response had a faster onset and more transient action than the cAMP counterpart. It is suggested that NA released from noradrenergic nerve endings regulates transepithelial Cl- secretion in the epididymis thereby providing the specialized millieu vital for sperm storage and maturation.
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PMID:Biphasic short-circuit current response to noradrenaline mediated by Ca2+ and cAMP in cultured rat epididymal epithelium. 801 89

An enzymohistochemical and immunohistochemical study of the efferent ducts was performed in normal adult men. The epithelium consists of two types of columnar cells: principal cells (PCs) and ciliated cells (CCs), and is surrounded by a lamina propria (LP) with cells arranged circularly (LPCs). Enzymohistochemical study revealed more intense activity of succinic dehydrogenase, NADP, and ATPase in the CCs than in the PCs. The LPCs also showed an intense reaction for NADP and ATPase. Acid phosphatase activity was only intense in the apical cytoplasm of PCs. Immunohistochemical study revealed that antibodies to oestradiol receptor-related protein (ER-D5) immunostained the PCs and CCs intensely and the LPCs weakly. AE1/AE3 antibodies (which stain keratins nos. 1-8 and 14, 15 and 19) immunostained the PCs intensely, but was negative in both CCs and LPCs. Antibodies to keratin Ks.4.62 (which stain keratin no. 19) immunostained PCs and CCs but not LPCs. Epithelial membrane antigen antibodies (EMA) immunostained the adluminal surface and apical cytoplasm of PCs. Anti-vimentin antibodies immunostained the cytoplasm of PCs and CCs weakly as well as isolated cells in the LP. Antibodies to desmin immunostained most LPCs. Antibodies to collagen IV immunostained the basal lamina and many extracellular spaces in the LP, mainly around the LPCs. The differences between the enzymohistochemical and immunohistochemical patterns of the efferent ducts and those of the epididymis may help to explain functional differences along the epididymis.
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PMID:Enzymohistochemical and immunohistochemical study of the human efferent ducts. 827 25

An acidic luminal pH (ref. 1-3) is involved in sperm maturation, and in maintaining sperm in an immotile state in the epididymis and vas deferens (2,4-6). Neutralization by prostatic fluid is one of a complex series of events that triggers sperm motility (2,7,8). Failure of the acidification mechanism might, therefore, result in poor sperm maturation, premature motility and infertility. We have shown that a vacuolar (H+)-ATPase is expressed at high levels on the luminal plasma membrane of specialized cells in the epididymis (9), which closely resemble acid-secreting kidney intercalated cells (10,11). We now show that similar cells are also present in the vas deferens, and that a bafilomycin-sensitive proton flux can be detected using a noninvasive proton-selective vibrating probe. Up to 80% of the net proton secretion in the vas deferens is inhibited by bafilomycin, consistent with a major role of a vacuolar-type (H+)-ATPase in this process. This acidification mechanism is a potential target for novel strategies aimed at modulating the acidification capacity of parts of the male reproductive tract and, therefore, in regulating male fertility.
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PMID:Acidification of the male reproductive tract by a proton pumping (H+)-ATPase. 859 61

Effects of oral administration of mercuric chloride (HgCl2, 1.25 mg/kg) daily for 30 d on the mouse testis, vas deferens, epididymis, and cauda epididymal sperm were investigated. Testis, vas deferens, and epididymis functions were evaluated with respect to sperm count, motility, and viability, and biochemical tests, including succinate dehydrogenase (SDH), adenosine triphosphatase, sialic acid, protein, cholesterol, and glycogen levels in these tissue. Sperm morphology and sperm nuclear integrity were evaluated with standard staining methods. Treatment did not affect whole body and tissue weights. Sperm parameters and fertility were reduced by HgCl2 and most of the biochemical parameters declined. Morphologic histologic alterations were also observed in the tissues studied. All parameters partially recovered after withdrawal of HgCl2 for 45 d.
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PMID:Reversible effects of mercuric chloride on reproductive organs of the male mouse. 891 13

Proton-motive forces are thought to be less important than sodium-motive forces in energizing animal membranes. On the supply side, proton-motive forces across mitochondrial inner membranes are well-known energizers of ATP synthesis, catalyzed by F-type ATP synthases. However, on the demand side, proton-motive forces, generated from ATP by V-ATPases, are not widely accepted as energizers of animal membranes; instead, sodium-motive forces, generated by P-ATPases, are thought to predominate. During the 1980s, Anraku, Nelson, Forgac and others showed that proton-motive forces from H+ V-ATPases energize endomembranes of all eukaryotic cells; in most cases, chloride ions accompany the protons and the output compartment is acidified. Unexpectedly, numerous examples of animal plasma membrane energization by proton-motive forces are now appearing. In many insect epithelia, H+ V-ATPases generate transmembrane voltages which secondarily drive sensory signalling, fluid secretion and even alkalization, rather than acidification. Plasma membranes of phagocytes and osteoclasts as well as polarized membranes of epithelia in vertebrate kidney, bladder and epididymis, even apical membranes of frog skin epithelial cells, are now known to be energized by proton-motive forces. The list of proton-energized animal plasma membranes grows daily and includes cancer cells. The localization of H+ V-ATPases either on endomembranes or on plasma membranes may reflect a key event in their evolution. Proton-motive ATPases, like the H+ A-ATPases in present-day archaebacteria, appear to be ancestors of both H+ F-ATP synthases and H+ V-ATPases. On the basis of a greater than 25% overall sequence identity and much higher identity in the nucleotide-binding and regulatory sites, Nelson and others have argued that the A and B subunits of V-ATPases, like the corresponding beta and alpha subunits of F-ATP synthases, derive from common 'A-ATPase-like' ancestral subunits. They postulate that oxygen, introduced into the earth's atmosphere by cyanobacteria, was a selective agent as these key subunits diverged during evolution. Forgac has focused the issue more sharply by showing that the catalytic 'A' subunit of H+ V-ATPases has tow key sulfhydryl residues that are proximal to each other in the tertiary structure; these residues form a disulfide bond under oxidizing conditions, thereby inactivating the enzyme. The corresponding beta subunit of H+ F-ATPases lacks such sulfhydryl residues. Perhaps because their plasma membranes are the site of oxygen-dependent ATP synthesis, which would select against their sulfhydryl-containing regulatory sites, eubacterial cells lack H+ V-ATPases. This retention of the regulatory cysteine residue in the active sites during evolution may explain why H+ V-ATPases. are commonly found in the reducing atmosphere of the cytoplasm, where they would be active, rather than in the putatively oxidizing atmosphere of many plasma membranes, where they would be inactive. It may also explain why animal plasma membrane H+ V-ATPases are commonly found in 'mitochondria-rich' cells. We suggest that the high oxygen affinity of cytochrome oxidase leads to localized reducing conditions near mitochondria which would allow H+ V-ATPases to remain active in plasma membranes of such cells. Moreover, this 'redox modulation mechanism' may obviate the need to evoke two types of enzyme to explain selective targeting of H+ V-ATPases to plasma membranes or endomembranes: membrane that contains a single form of H+ V-ATPase may cycle between the membranes of the cytoplasmic organelles and the cell surface, the enzyme being active only when reducing conditions remove the disulfide bonding restraint.
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PMID:Animal plasma membrane energization by chemiosmotic H+ V-ATPases. 905 Feb 28

Specialized proton-secreting cells play important physiological roles in a variety of tissues. On the basis of the immunocytochemical detection of carbonic anhydrase and V-ATPase in distinct epithelial cells of the epididymis and vas deferens, we predicted that the vacuolar V-ATPase that is located on the apical membrane of these cells should be a major contributor to luminal acidification in parts of the male reproductive tract. Physiological studies using the proton-selective vibrating probe in the vas deferens confirmed this hypothesis. As discussed recently, maintenance of the pH of the reproductive tract is probably under tight physiological control, by analogy with the situation in the kidney. Manipulation of luminal pH might, therefore, provide a point of intervention for the regulation of male fertility. In addition, it is possible that some cases of unexplained male infertility might result from defective acidification, resulting either from pathological states or potentially from environmental factors that may inhibit proton secretory pathways.
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PMID:Role of V-ATPase-rich cells in acidification of the male reproductive tract. 905 Feb 33

Several transporting epithelia in vertebrates and invertebrates contain cells that are specialized for proton or bicarbonate secretion. These characteristic 'mitochondria-rich' (MR) cells have several typical features, the most important of which is an extremely high expression of a vacuolar-type proton-pumping ATPase (H+V-ATPase) both on intracellular vesicles and on specific domains of their plasma membrane. Physiological modulation of proton secretion is achieved by recycling the H+V-ATPase between the plasma membrane and the cytoplasm in a novel type of nonclathrin-coated vesicle. In the kidney, these cells are involved in urinary acidification, while in the epididymis and vas deferens they acidify the luminal environment to allow normal sperm development. Osteoclasts are non-epithelial MR cells that use H+V-ATPase activity for bone remodeling. In some insects, similar cells in the midgut energize K+ secretion by means of a plasma membrane H+V-ATPase. This review emphasizes important structural and functional features of proton-secreting cells, describes the tissue distribution of these cells and discusses the known functions of these cells in their respective epithelia.
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PMID:Mitochondria-rich, proton-secreting epithelial cells. 911

Thiram was administered to male rats through gavage at doses 5, 10 and 25 mg/kg/day for 180 and 360 days. Thiram has caused marginal increase in the relative weight of testes and epididymis and decrease in the weight of seminal vesicle and prostate. Marked degenerative changes were observed in seminiferous tubules together with alterations in testicular enzyme profile. The activity of testicular enzymes such as ACP, SDH and ATPase (Na+ + K+ dependent) was decreased whereas activity of LDH, G-6-PDH and ALP increased. The levels of serum cholesterol and testicular free sialic acid were enhanced, while the level of testicular protein was lowered. It is evident from the present study that long term treatment of thiram at tested dose levels has resulted in dose and time dependent morphological and biochemical changes in testes of rat.
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PMID:Testicular toxicity in rat to repeated oral administration of tetramethylthiuram disulfide (Thiram). 971 50

The lumen of the epididymis is the site where spermatozoa undergo their final maturation and acquire the capacity to become motile. An acidic luminal fluid is required for the maintenance of sperm quiescence and for the prevention of premature activation of acrosomal enzymes during their storage in the cauda epididymis and vas deferens. We have previously demonstrated that a vacuolar H+-ATPase [proton pump (PP)] is present in the apical pole of apical and narrow cells in the caput epididymis and of clear cells in the corpus and cauda epididymis and that this PP is responsible for the majority of proton secretion in the proximal vas deferens. We now show that PP-rich cells in the vas deferens express a high level of carbonic anhydrase type II (CAII) and that acetazolamide markedly inhibits the rate of proton secretion by 46.2 +/- 6.1%. The rate of acidification was independent of Cl- and was strongly inhibited by SITS under both normal and Cl--free conditions (50.6 +/- 5.0 and 57. 5 +/- 6.0%, respectively). In the presence of Cl-, diphenylamine-2-carboxylate (DPC) had no effect, whereas SITS inhibited proton secretion by 63.7 +/- 11.3% when applied together with DPC. In Cl--free solution, DPC markedly inhibited proton efflux by 45.1 +/- 7.6%, SITS produced an additional inhibition of 18.2 +/- 6.6%, and bafilomycin had no additive effect. In conclusion, we propose that CAII plays a major role in proton secretion by the proximal vas deferens. Acidification does not require the presence of Cl-, but DPC-sensitive Cl- channels might contribute to basolateral extrusion of HCO-3 under Cl--free conditions. The inhibition by SITS observed under both normal and Cl--free conditions indicates that a Cl-/HCO-3 exchanger is not involved and that an alternative HCO-3 transporter participates in proton secretion in the proximal vas deferens.
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PMID:Proton secretion in the male reproductive tract: involvement of Cl--independent HCO-3 transport. 975 67


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