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SHIFTS IN UBIQUINONE REDOX STATUS OF RAT BRAIN IN VITRO WITH CATIONIC STIMULATION
Author(s) -
Klicpera J. A.,
Hoffmann P. C.
Publication year - 1975
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1975.tb03673.x
Subject(s) - respiration , ouabain , stimulation , redox , substrate (aquarium) , chemistry , medicine , respiratory system , endocrinology , biochemistry , biology , inorganic chemistry , anatomy , sodium , ecology , organic chemistry
–Changes in respiratory rate, ubiquinone (Q) redox status, lactate and pyruvate levels in chopped rat telencephalon were studied after cationic stimulation of respiration. When chopped telencephalon was incubated with glucose as substrate, increasing the K + concentration from 5 m m to 55 m m was associated with a 57% increase in the respiratory rate and a reduction in Q redox status from 76% oxidized to 64% oxidized. Lactate increased by over 200%. Substitution of pyruvate for glucose with 5 m m ‐K + resulted in a respiratory rate that was 78% of that seen with glucose and 55 m m ‐K + . Increasing K + from 5 m m to 55 m m increased the respiratory rate by only 6%, with pyruvate as substrate. Q underwent a reduction that was half that seen with glucose. Ouabain largely prevented the K + ‐induced increase in respiratory rate with glucose as substrate, but Q was still reduced by 5 percentage points while lactate and pyruvate were unchanged. When respiration was uncoupled with 2,4‐dinitrophenol, increasing the K + concentration from 5 mM to 55 m m had no further effect on any of the metabolic parameters measured. Deletion of Ca 2+ from the medium resulted in an increase in respiration of 18%, but neither the Q redox status nor the levels of lactate or pyruvate were significantly changed. The results demonstrate that the K + ‐induced stimulation of respiration results from a coordinated metabolic response whereas the stimulation of respiration associated with Ca 2+ depletion is probably mediated through ion fluxes at the cell membrane and activation of Na + ‐K + ‐activated ATPases.