Influence of various lipophilic drugs on brain mitochondrial hexokinase

Solubilization of Hexokinase Activity by an Effect of Thiopental on the Mitochondrial Membrane

“…3). In addition, it seems noteworthy that chlorpromazine did not enhance the soluble hexokinase activity in vivo [6]. When extremely high concentra tions of chlorpromazine (100pmol/l in the perfusion medium) were administered to the isolated perfused rat brain, there was a mea surable decrease rather than any increase in soluble hexokinase activity in brain tissue.…”

“…Homogenization was carried out in icecold 0.02 mol/1 HEPES-bufTer containing 0.25 mol/l sucrose (pH 7.5) by means of a tight fitting PotterElvehjem homogenizer. Fractionation has already been described by llanke et al [6].…”

“…It has been demonstrated in previous studies that hexokinase activity is solubilized in anesthesia [1][2][3][4][5][6]. It is still uncertain whether anesthetics in vivo affect directly mitochondrial bound hexokinase activity or whether solubilization is indirectly achieved by the metabolic state changed in anesthesia.…”

“…After 1 h of incuba tion the medium was sucked off and the cells were harvested by scraping with a rubber policeman into ice-cold HEPES-sucrose solution. Homogenization and hexokinase fractionation [6] was done imme diately thereafter. Hexokinase activity was measured in the crude homogenate and in the supernatant.…”

“…A mitochondrial fraction prepared from the brains of untreated rats [6], liver mitochondria with bound brain hexokinase [ 10] and C-l 300 neuroblastoma cells were used. Aliquots of the brain mitochondrial frac tion and the liver mitochondria with bound hexoki nase were suspended in the HEPES-bufTer (sec above) and incubated for 30 min at 30 °C (brain) or 15 min at 25 "C (liver) with the drugs dissolved in 0.25 mol/1 sucrose (controls received sucrose only).…”