Phospholipase A₂ Activity in Endotoxin Shock Rats Model

Tsutomu Nomura, Koji Sasajima, Masao Miyashita, Yuuichi Sugisaki*

First Department of Surgery, Nippon Medical School and First Department of Pathology*, Nippon Medical School

It has been suggested that phospholipase A₂ (PLA₂) plays an important role in the development of shock in patients with endotoxemia. The PLA₂ activity was reported to be elevated in the serum of patients with endotoxin shock. To determine the origin and mechanism of the elevated PLA₂ activity, we made an endotoxin shock model in rats by injecting 5 mg of lipopolysaccharide (LPS) per kg, intravenously. Serum PLA₂ activity increased from 194±25 to 359±56 pmol/ml/min (mean±SEM) 30 min after the LPS injection. The PLA₂ activity in the liver homogenates also increased from 7.8±0.6 to 10.2±0.2 pmol/mg protein/min after 30 min. The increased PLA₂ activity was shown to be heat labile and calcium-ion dependent. Ultrastructural enzymehistochemically, PLA₂ activity was found in the lysozome membrane of damaged hepatocytes and Kupffer's cells. These results suggest that the increase in heat labile and calcium-ion dependent PLA₂ activity is related to tissue damage in the endotoxin shock model.

Key words
endotoxin shock model, phospholipase A₂ activity, enzyme histochemistry of phospholipase A₂

Reprint requests
Tsutomu Nomura First Department of Surgery, Nippon Medical School
1-1-5 Sendagi, Bunkyo-ku, Tokyo, 113 JAPAN

Accepted
September 14, 1994

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