The effect of idebenone on the lateral mobility of proteins in hepatocyte plasma membrane of old rats as revealed by fluorescence recovery after photobleaching (FRAP) technique using an endogenous label.
The average lateral diffusion constant of proteins (D) in the cell membrane of hepatocytes has been measured in liver smears by fluorescence recovery after photobleaching (FRAP) based on the so-called peroxide-induced autofluorescence (PIAF) deriving from the oxidation of riboflavin bound to membrane proteins. It has been shown before that D displays a significant negative linear age-correlation. The in vivo effect of idebenone was tested on this parameter. Old (23.7 months at killing) male Fischer 344 rats received 50 mg of the drug per kg body weight per os through gastric tube, suspended in 5% gum arabic solution (Verum I group) or the same dose and form of idebenone completed by 80 mg centrophenoxine per kg body weight (Verum II group) for 35 days. D was measured on a double blind basis in hepatocyte plasma membrane of the Verum or Placebo (5% gum arabic, only) groups. A significant increase of D (29.6%) was induced by idebenone in the Verum I group; nevertheless, even the Placebo group displayed a moderate, but statistically significant increase of D (10.7%). The Verum II group showed a total of 39.6% increase in the value of D. The loss of body weight being characteristic for these animals at the age of around 2 years was between 0.87 and 1.06 g/day, whereas in other experiments higher values (1.77 g/day) were observed in the controls.
Zs -Nagy
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First Laboratory of Clinical Physiology, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo-173, Japan.
Ohta
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Kitani
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