The effect of idebenone on the passive K+ and Rb+ permeability of the brain cell membranes of CFY rats as revealed by the Rb+-discrimination ratio.
Rubidium (Rb(+)) uptake and release of brain cortical neurons of adult (12-15 month old), normal, female CFY rats were studied in placebo- and idebenone-treated animals. Treatment period was up to 5 weeks, with 50 mg/kg bw/day idebenone (oxidized form) suspended in 5% gum arabic (verum-group), or only with the latter solvent (placebo-group). Rb(+) can replace up to 60% of the intracellular K(+), and can be used as a tracer of the K(+) movement across the cell membrane. Loading with RbCI was performed from the 3rd week of the idebenone treatment by daily intraperitoneal injections of a dose of 300 mg/kg bw, for 14 days. During the subsequent Rb(+)-release period, the so-called Rb(+)/K(+) discrimination ratio (DR) (Relman et al., 1957, J. Clin. Invest., 36, 1249) was determined on the 3rd and 8th days. Rb(+) and K(+) contents were measured by means of bulk specimen X-ray microanalysis in the intracellular water of brain cells and by atomic absorption spectrophotometry in the serum, in 3-4 animals per group, whereas these concentrations in the cerebrospinal fluid were calculated on the basis of known serum/liquor distribution factors. Normal aging causes a marked increase of DR in brain and liver cells. The values of DR obtained in both placebo and verum groups were identical with those of the age-matched, completely untreated controls. It is important to stress that the subacute idebenone treatment did not cause any deterioration of this parameter, i.e., under the given conditions idebenone does not affect the cell membrane passive Rb(+) and K(+) permeability characteristics in the neurons of adult, normal, female CFY rats.
Lustyik
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Fritz Verzár International Laboratory for Experimental Gerontology, Hungarian Section, University Medical School, Debrecen H-4012, Hungary.
Szállási
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Jeney
F
F
Zs -Nagy
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I