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  • 1985-1989  (1)
  • 1980-1984  (1)
  • 1975-1979
  • Ca++-ATPase  (1)
  • Electromagnetic flowmetry  (1)
  • 1
    ISSN: 1432-0878
    Keywords: Ca++-ATPase ; K+-NPPase ; Na+-K+ATPase ; Ultracytochemistry ; Photoreceptor cells, retinal ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ca++-ATPase activity was demonstrated histochemically at light- and electron-microscopic levels in inner and outer segments of retinal photoreceptor cells of the guinea pig with the use of a newly developed one-step lead-citrate method (Ando et al. 1981). The localization of ouabain-sensitive, K+-dependent p-nitrophenylphosphatase (K+-NPPase) activity, which represents the second dephosphorylative step of the Na+-K+-ATPase system, was studied by use of the one-step method newly adapted for ultracytochemistry (Mayahara et al. 1980). In retinal photoreceptor cells fixed for 15 min in 2% paraformaldehyde the electron-dense Ca++-ATPase reaction product accumulated significantly on the inner membranes of the mitochondria but not on the plasmalemma or other cytoplasmic elements of the inner segments. The membranes of the outer segments remained unstained except the membrane arrays in close apposition to the retinal pigment epithelium. The cytochemical reaction was Ca++- and substrate-dependent and showed sensitivity to oligomycin. When Mg++-ions were used instead of Ca++-ions, a distinct reaction was also found on mitochondrial inner membranes. In contrast to the localization of the Ca++ -ATPase activity, the K+-NPPase activity was demonstrated only on the plasmalemma of the inner segments, but not on the mitochondria, other cytoplasmic elements or the outer segment membranes. This reaction was almost completely abolished by ouabain or by elimination of K+ from the incubation medium.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 25 (1987), S. 386-390 
    ISSN: 1741-0444
    Keywords: Central caudal artery ; Electrical impedance plethysmography ; Electromagnetic flowmetry ; Peripheral blood flow ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The impedance Z, the derivative of Z with respect to time t, dZ/dt, and blood flow F have been measured simultaneously in the central caudal artery of a series of anaesthetised rats. The results of the experiments were expressed in the relationship derived from the Windkessel theory where f(t)=adz(t)/dt+βz(t), in which α and β are constants and f(t) and z(t) express the pulsating fractions in the blood flow F and the impedance Z, respectively. The correlation between the peak-to-peak values of f(t) and of adz(t)/dt+βz(t) was 0·96. The correlation between the mean flow fo and the peak-to-peak value of f(t) was 0·74. Furthermore, even when the mean flow was zero, adz(t) still existed. The theoretical model was tested against volume flow measurements made using an electromagnetic flowmeter and was found to correlate well. Theoretical estimates of vessel calibre also accord with measured values.
    Type of Medium: Electronic Resource
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