J.Jpn. Surg. Soc.. 86(1): 23-31, 1985
Original article
THE MECHANISM OF ACTION OF E.COLI ENDOTOXIN ON OXIDATIVE PHOSPHORYLATION OF RAT LIVER MITOCHONDRIA
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1) Department of 1st. Surgery, Yamagata University School of Medicine, Yamagata, Japan Shuichi Ishiyama1), Koichi Hiraga2), Masaru Tsukamoto1) |
The respiratory control index (RCI) was significantly decreased by preincubation of mitochondria for 20min. at 30℃ in the presense of the endotoxin, which repressed dose-dependently the state 3 respiration. The extent of the repression of this state 3 respiration was comparable with that of the exchange reaction of adenine nucleotide. The endotoxin, however, did not inhibit several mitochondrial enzymes including the electron transport system at the enzyme level.
The exchange reaction and the number of the ADP-binding sites of the adenine nucleotide carrier were assayed using［14C］ADP and［3H］carboxyatractyloside, respectively. The exchange reaction was repressed by 72％ and the number of binding site of carboxyatractyloside was decreased by 20％ by the endotoxin (100μg/mg mitochondrial protein).
These effects of endotoxin on the adenine nucleotide carrier were additionally enhanced by the Ca2＋ ion. The occurence of these effects was prevented by EGTA or dibucaine, a potent inhibiter of phospholipase A2.
These results suggested that the endotoxin may activate phospholipase A2 which may harm the lipid layer of the mitochondrial membrane.
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