ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
—(1) Cerebral slices were incubated in Ca2+-free media or in media which contained 2.8 mm-Ca2+. Omission of Ca2+ brought about a drop in creatine phosphate content of 28 per cent, as well as a drop of 3–10 per cent in non-inulin K+ content. There was little change in content of 10-min phosphate or of non-inulin Na+.(2) Ouabain in concentrations of to M increased the loss of K+ from the slice and caused a rise in Na+ content. The changes were most marked in Ca2+-free media. Creatine phosphate levels were depressed by ouabain both in the presence or absence of Ca2+. In the absence of Ca2+, the lowering of phosphocreatine did not occur until significant shifts in K+ had taken place. In contrast, slices incubated in Ca2+-containing media lost creatine phosphate and K+ at about the same rate.(3) When ouabain and labelled phosphate were added simultaneously, there was little difference in the rate of incorporation of label into creatine phosphate in media which differed in Ca2+ concentration. However, incorporation of azP-labelled phosphate into creatine phosphate was decreased by 30–40 per cent in media which lacked Ca2+ when ouabain was added 15 min prior to the labelled phosphate. This change was not observed when the media contained Ca2+.(4) Ouabain did not affect oxidative phosphorylation or respiratory control when added directly to bovine brain mitochondrial preparations.(5) The results suggest that the previously observed depression of respiration brought about by ouabain in Ca2+-deficient media is not a good indicator of the proportion of the cell's metabolism used for active cation transport. Under these conditions, the inhibition of cation transport is accompanied by a drop in slice content of high-energy phosphate which may represent a secondary effect of ouabain, or of cytoplasmic alterations brought about by ouabain, on energy-producing processes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1968.tb06175.x
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