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  • 1
    Electronic Resource
    Electronic Resource
    Actions of cadmium on basolateral plasma membrane proteins involved in calcium uptake by fish intestine (1992)
    Springer
    The journal of membrane biology 127 (1992), S. 161-172 
    Details
    ISSN: 1432-1424
    Keywords: cadmium ; Ca2+-ATPase ; (Na++K+)-ATPase ; Na+/Ca2− exchange competitive inhibition ; teleost fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The inhibition of Ca2−-ATPase, (Na++K+)-ATPase and Na+/Ca2+ exchange by Cd2+ was studied in fish intestinal basolateral plasma membrane preparations. ATP driven 45Ca2+ uptake into inside-out membrane vesicles displayed a K m for Ca2+ of 88±17 nm, and was extremely sensitive to Cd2+ with an IC50 of 8.2±3.0 pM Cd2+, indicating an inhibition via the Ca2+ site. (Na++K+)-ATPase activity was half-maximally inhibited by micromolar amounts of Cd2+, displaying an IC50 of 2.6±0.6 μm Cd2+. Cd2+ ions apparently compete for the Mg2+ site of the (Na− +K+)-ATPase. The Na+/Ca2+ exchanger was inhibited by Cd2+ with an IC50 of 73±11 nm. Cd2+ is a competitive inhibitor of the exchanger via an interaction with the Ca2+ site (K i = 11 nm). Bepridil, a Na+ site specific inhibitor of Na+/Ca2+ exchange, induced an additional inhibition, but did not change the K i of Cd2+. Also, Cd2+ is exchanged against Ca2+, albeit to a lesser extent than Ca2+. The exchanger is only partly blocked by the binding of Cd2+. In vivo cadmium that has entered the enterocyte may be shuttled across the basolateral plasma membrane by the Na+/Ca2+ exchanger. We conclude that intracellular Cd2+ ions will inhibit plasma membrane proteins predominantly via a specific interaction with divalent metal ion sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231504
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  • 2
    Electronic Resource
    Electronic Resource
    Prolactin and Serum Osmolality of Hypophysectomized Killifish, Fundulus heteroclitus , in Fresh-water (1966)
    [s.l.] : Nature Publishing Group
    Nature 209 (1966), S. 1040-1041 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Preliminary data, reported in this communication, demonstrate that injections of ovine prolactin, at a suitable dose, enable hypophysectomized F. heteroclitus to maintain normal serum osmolality. Serum was taken from selected groups of fish the failure or survival of which in fresh-water has been ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/2091040a0
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  • 3
    Electronic Resource
    Electronic Resource
    Modification by solvents of the action of nifedipine on calcium channel currents in neuroblastoma cells (1992)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 345 (1992), S. 478-484 
    Details
    ISSN: 1432-1912
    Keywords: Nifedipine ; T Channel currents ; Solvents ; Neuroblastoma cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of nifedipine dissolved in different solvents on the two types of calcium channel currents in neuroblastoma cells was investigated using the whole cell version of the patch clamp technique. Nifedipine dissolved in dimethylsulfoxide (nifedipine/DMSO) decreased the transient calcium channel (T channel) current by 50% at a concentration of 10 μM. This inhibitory effect was concentration-dependent and reversible. In contrast, T channel currents were not inhibited by nifedipine at a similar concentration dissolved in acetone or ethanol. Further experiments were carried out with dried nifedipine/DMSO. Dried nifedipine/DMSO powder re-dissolved in acetone or ethanol at a concentration of 10 μM decreased the T channel current by 32% and 37%, respectively. In addition, within the concentration range of 10 nM to 100 μM nifedipine/DMSO inhibited the long-lasting calcium channel (L channel) current more effectively than did nifedipine dissolved in acetone. The concentration of solvent (DMSO, ethanol, acetone) in the bath was fixed at 0.3% to reach different final concentrations of nifedipine. Solvents alone at a final concentration of 0.3% did not show any effect on T or L channel currents. UV absorbance measurements indicated that the combination of nifedipine, solvent and bath solution did not result in precipitation of the dihydropyridine during the experimental protocol. It is concluded that when DMSO is used as the solvent, nifedipine is not only a more effective L channel antagonist but also a T channel antagonist in neuroblastoma cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00176628
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  • 4
    Electronic Resource
    Electronic Resource
    Branchial calcium uptake: possible mechanisms of control by stanniocalcin (1993)
    Springer
    Fish physiology and biochemistry 11 (1993), S. 205-215 
    Details
    ISSN: 1573-5168
    Keywords: fish gills ; calcium transport ; Ca-pump ; Ca-ATPase ; stanniectomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Abstract The branchial Ca2+ uptake by teleost fish is under inhibitory control by the hormone stanniocalcin (STC) which is generated by the corpuscles of Stannius (CS). Removal of the CS in North American eel, Anguilla rostrata LeSueur, induced a rapid rise in blood calcium levels. Branchial Ca2+ influx following the extirpation of the CS (stanniectomy, STX) increased during the first four days and stayed elevated thereafter (in agreement with previous studies). The transepithelial potential (TEP) across the gills did not change after STX and this means that the electrochemical gradient for Ca2+ is less favourable for passive influx of Ca2+ in STX eel. Therefore, the Ca2+ influx in STX eels is a transcellular flux, with Ca2+ crossing the apical and basolateral membrane barrier. The kinetics of ATP-driven Ca2+-transport across basolateral plasma membranes from eel gills did not change after STX. Thus, the increased Ca2+-influx after STX is not correlated with changes in ATP-dependent Ca2+-extrusion across the basolateral membrane, suggesting a regulation at the apical membrane. Moreover, STC did not affect ATP-driven Ca2+-transport in isolated basolateral membranes (in vitro). STC (0.1 nM) reduced cAMP levels in dispersed eel gill cells. It had no significant effect on the IP3 levels in these cells. We postulate that STC controls the permeability to Ca2+ of the apical membranes of the Ca2+ transporting cells of fish gills by controlling second messenger operated Ca2+ channels in the apical membrane.
    Notes: Résumé L'entrée de calcium au niveau des branchies est sous le controle inhibiteur de la stanniocalcine (STC) qui est synthétisée au niveau des corpuscules de Stannius (CS). L'ablation des CS chez l'anguille d'Amérique du Nord, Anguilla rostrata LeSueur, induit une augmentation rapide des niveaux de calcium dans le sang. Le flux entrant branchial de calcium consécutif à l'ablation des CS (stanniectomie, STX) augmente pendant les 4 premiers jours et reste élevé au-delà (en accord avec des études antérieures). Le potentiel transépithélial (TEP) à travers les branchies ne change pas après STX, ceci indiquant que le gradient électrochimique du Ca2+ est moins favorable pour le flux entrant passif du Ca2+ chez l'anguille STX. En conséquence, le flux entrant de Ca2+ chez l'anguille STX est un flux transcellulaire, avec le Ca2+ traversant la barrière membranaire apicale et basolatérale. La cinétique du transport de Ca2+ conduit par l'ATP à travers les membranes plasmatiques basolatérales de branches d'anguille n'est pas modifiée après STX. Ainsi, l'augmentation du flux entrant de Ca2+ après STX n'est pas corrlée avec des modifications de l'excrétion de Ca2+ conduit par l'ATP à travers la membrane basolatérale, suggérant donc une régulation au niveau de la membrane apicale. De plus, la STC ne modifie pas le transport de Ca2+ conduit par l'ATP dans des membranes basolatérales isolées (in vitro). La STC (0.1 nM) réduit les niveaux d'AMPc dans des cellules dispersées de branchies d'anguille. Cette hormone n'a pas d'effet significatif sur les niveaux d'IP3 dans ces cellules. Nous suggérons que la STC régule la perméabilité au Ca2+ des membranes apicales des cellules branchiales transporteuses de Ca2+ en controlant un second messager agissant sur les canaux calciques de la membrane apicale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004568
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  • 5
    Electronic Resource
    Electronic Resource
    Localization of calcium regulatory hormones in fish (1989)
    Springer
    Fish physiology and biochemistry 7 (1989), S. 337-342 
    Details
    ISSN: 1573-5168
    Keywords: parathyroid hormone (PTH) ; calcitonin ; calcitonin gene-related peptide (CGRP) ; hypocalcin ; radioimmunoassay ; immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Immunocytochemical localization of hypocalcin, a hypocalcemic factor in the corpuscles of Stannius (CS), in American eels was examined at the light (ABC method) and electron microscopic (protein A-gold technique) levels with the specific antiserum raised against purified rainbow trout hypocalcin. Only type 1 cells in the CS were immunoreactive in the light microscopic immunocytochemistry. At the electron microscopic level, however, hypocalcin immunoreactivity was observed in secretory granules of both type 1 and type 2 cells. Our findings may indicate that type 1 cells are the main source of hypocalcin, but that type 2 cells also produce it, suggesting that the presence of two cell types reflects different physiological conditions of a single cell type, rather than functionally different cell types. In addition, we summarize our recent data on the localization of other calcium regulatory, or putative calcium regulatory, hormones in fish: parathyroid hormone, calcitonin and calcitonin gene-related peptide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004726
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  • 6
    Electronic Resource
    Electronic Resource
    Studies on teleost corpuscles of Stannius: Physiological and biochemical aspects of synthesis and release of hypocalcin in trout, goldfish and eel (1989)
    Springer
    Fish physiology and biochemistry 7 (1989), S. 343-349 
    Details
    ISSN: 1573-5168
    Keywords: trout ; goldfish ; eel ; fresh water ; seawater ; hypercalcemia ; hypocalcin ; glycoprotein ; secretory protein ; concanavalin-A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hypercalcemia (induced by CaCl2-injection or seawater exposure of the fish) reduced the hypocalcin content of corpuscles of Stannius (CS) in trout, goldfish and eel; concomitantly the synthetic activity of CS of hypercalcemic fish, as determinedin vitro, was enhanced. The monomeric forms of prohypocalcin and of hypocalcin of trout and goldfish are 32 and 28 kDA Mr glycoprotein species respectively; those of the eel are 2 kDa bigger,viz. 34 and 30 kDa respectively. Moreover, eel CS producein vitro an enigmatic 70 kDa glycoprotein with affinity for concanavalin-A. It is concluded that plasma calcium levels control storage and synthesis rates of hypocalcin in the CS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004727
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  • 7
    Electronic Resource
    Electronic Resource
    Immunocytochemical localization of hypocalcin in the endocrine cells of the corpuscles of Stannius in three teleost species (trout, flounder and goldfish) (1989)
    Springer
    Cell & tissue research 255 (1989), S. 651-656 
    Details
    ISSN: 1432-0878
    Keywords: Corpuscles of Stannius ; Hypocalcin ; Immunohistochemistry ; Carassius auratus ; Hippoglossoides elassodon ; Salmo gairdneri
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to identify the cell-type responsible for the production of hypocalcin (the recently isolated hypocalcemic hormone of teleost fish), the corpuscles of Stannius (CS) of trout, flounder and goldfish, were immunocytochemically stained with antisera raised against trout hypocalcin. The secretory granules of the type-1 cells of the CS, considered to be the hypocalcin-producing cells, showed intense immunoreactivity in all species examined. However, in trout and flounder, the secretory granules produced by the type-2 cells, which have been suggested to represent a functionally different cell-type, also showed an intense immunoreactivity. In goldfish, no type-2 cells were observed. We tentatively conclude that type-1 and type-2 cells represent structurally different forms of the same functional cell-type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218804
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  • 8
    Electronic Resource
    Electronic Resource
    Localization of calcitonin gene-related peptide in the small intestine of various vertebrate species (1989)
    Springer
    Cell & tissue research 258 (1989), S. 35-42 
    Details
    ISSN: 1432-0878
    Keywords: Calcitonin gene-related peptide (CGRP) ; Small intestine ; Smooth muscle ; Mouse (ICR), rat (Sprague-Dawley), guinea pig, domestic fowl, Iguana iguana (Lacertilia), Rana catesbeiana (Anura), Salmo gairdneri (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Calcitonin gene-related peptide (CGRP) was found extensively in the small intestine of both non-mammalian and mammalian vertebrates using radioimmunoassay and immunocytochemistry. By radioimmunoassay, the levels of CGRP in rats, mice, chickens, bullfrogs and rainbow trout were found to range from 91.5 to 419.1 ng/g tissue. To localize CGRP in the small intestine, we used three different tissue preparations for immunocytochemistry: whole-mount preparations, and frozen and Paraplast sections. The combination of three tissue preparations made it easier to visualize the three-dimensional structure and reduced the possibility of missing the immunoreaction. Immunoreactive cell bodies were found in the plexi in the mammalian species. Dense and regular networks of CGRP fibers were observed in the smooth muscle layers, when examined in whole-mount preparations. In non-mammalian species, however, immunoreactive cell bodies could not be detected, although immunoreactive fibers were present, forming less dense and regular networks. Our results indicate that CGRP-immunoreactive fibers are present in the smooth muscle layers of the intestine from fish to mammals, suggesting that CGRP may be involved in regulating gastrointestinal smooth muscles in vertebrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223142
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  • 9
    Electronic Resource
    Electronic Resource
    Electron-microscopic study of innervation of smooth muscle cells surrounding collecting tubules of the fish kidney (1984)
    Springer
    Cell & tissue research 238 (1984), S. 307-312 
    Details
    ISSN: 1432-0878
    Keywords: Innervation ; Smooth muscle ; Fish ; Kidney ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the collecting tubules of the trout and killifish kidney was studied. These tubules are surrounded by layers of smooth muscle cells which are commonly innervated. The nerve terminals contain synaptic vesicles and, occasionally, a few dense-cored granules as well. Capillaries occur in the connective tissue space between these smooth muscle cells and the collecting tubule. Epithelial cells of the collecting tubules contain abundant mitochondria and a well developed membrane system displaying parallel arrays, and were considered to be actively involved in the transport of materials. In the trout, the collecting tubules contain peculiar cells in addition to regular tubule cells. The fine structure of these peculiar cells is highly reminiscent of that of gill chloride cells. The significance of these findings may be summarized as follows: If the smooth muscles around the collecting tubule contract under neural influence, intratubular pressure may be increased and, thus affect glomerular filtration rate. The contraction of these muscles may also cause the collapse of peritubular capillaries, affecting the transport activity of tubule cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217302
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  • 10
    Electronic Resource
    Electronic Resource
    Electron microscopic study of the innervation of the renal tubules and urinary bladder epithelium in Rana catesbeiana and Necturus maculosus (1984)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 181 (1984), S. 143-153 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fine structure of the kidney and the bladder of the bullfrog (Rana catesbeiana), the bullfrog tadpole, and the mudpuppy (Necturus maculosus) were studied with special attention to the innervation of renal tubule cells and bladder epithelial cells. In the bullfrog kidney, nerve terminals and varicosities were frequently associated with the tubule cells, apparently in an increasing order from the proximal tubule to the connecting tubule. Although these terminals and varicosities did not directly contact the tubular cell membrane, an aggregation of synaptic vesicles on the side facing the tubule was considered as morphological evidence that neurotransmitter can be released here and can affect the transport activity of the tubule cells. The association of nerve varicosities with canaliculi cells in the connecting tubule was also demonstrated. In the bullfrog tadpoles, renal tubule cells were occasionally innervated. In the mudpuppy, renal tubule cells were only poorly innervated. The epithelium of the bullfrog bladder was commonly innervated. Nerve terminals with synaptic vesicles were located very near basal cells and even contacted them directly on rare occasions. In the mudpuppy, the innervation of the bladder epithelium was observed infrequently. The bullfrog tadpoles did not possess an apparent bladder. In all materials studied, renal arterioles and bladder smooth muscle cells were innervated.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051810203
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