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  • 2005-2009  (2)
  • 1
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study was planned on the assumptions that different high-voltage activated calcium channels and/or the ability of mitochondria to take up Ca2+ could be responsible for different cytosolic Ca2+ concentrations ([Ca2+]c) and catecholamine release responses in adrenal chromaffin cells of bovine and mouse species. Short K+ pulses (2–5 s, 70 mm K+) increased [Ca2+]c to a peak of about 1 µm; however, in bovine cells the decline was slower than in mouse cells. Secretory responses were faster in mouse but were otherwise quantitatively similar. Upon longer K+ applications (1 min), elevations of [Ca2+]c and secretion were prolonged in bovine cells; in contrast [Ca2+]c in mouse cells declined three-fold faster and failed to sustain a continued secretion. Confocal [Ca2+]c imaging following a 50-ms depolarizing pulse showed a similar Ca2+ entry, but a rate of [Ca2+]c increase and a maximum peak significantly higher in bovine cells; the rate of dissipation of the Ca2+ wave was faster in the mouse. The mitochondrial protonophore CCCP (2 µm) halved the K+-evoked [Ca2+]c and secretory signals in mouse cells, but had little affect on bovine responses. We conclude that the relative densities of L (15% in bovine and 50% in mouse) and P/Q Ca2+ channels (50% in bovine and 15% in mouse) do not contribute to the observed differences; rather, the different intracellular distribution of Ca2+, which is strongly influenced by mitochondria, is responsible for a more sustained secretory response in bovine, and for a faster and more transient secretory response in mouse chromaffin cells. It seems that mitochondria near the plasmalemma sequester Ca2+ more rapidly and efficiently in the mouse than in the bovine chromaffin cell.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Berlin, Germany : Blackwell Verlag GmbH
    Anatomia, histologia, embryologia 34 (2005), S. 0 
    ISSN: 1439-0264
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The ultrastructure of the primary and secondary lamellae of gills was investigated in a marine teleost, the white croaker. The following cells were identified and briefly described: pavement cells, mucous cells, mitochondria-rich cells and rodlet cells. These cell types are present throughout the length of the lamellae. They are studied by means of a series of carbohydrate histochemical methods, including lectin procedures. Neutral sugars and substituted sialic acid were detected by means of periodic acid–borohydride reduction–saponification–periodic acid Schiff reaction (PA/Bh/KOH/PAS), saponification–selective periodic acid Schiff reaction (KOH/PA*S) and saponification–selective periodic acid–borohydride reduction–periodic acid Schiff reaction (KOH/PA*/Bh/PAS) histochemical techniques. A battery of seven lectins was used to study binding on tissue sections at the light microscopic level to characterize glycoconjugates in gills. The reaction to Canavalia ensiformis agglutinin (Con-A), Triticum vulgaris agglutinin (WGA), and Ricinus cummunis agglutinin-1 (RCA-1) was weak in pavement cells; unlike Con-A, the reaction to WGA and RCA-1 was more intense in mucous cells. Arachis hypogaea agglutinin (PNA) lectin showed a strong reaction in mucous cells. Ulex europaens agglutinin-1 (UEA-1) lectin was negative in all cell types. The lectin pattern was similar for both primary and secondary lamellae, except for PNA reaction, which was weak in the pavement cells of the secondary lamella and negative in the pavement cells of the primary lamella.
    Type of Medium: Electronic Resource
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