Kinetic characteristics of spontaneous lipid peroxidation in membranes isolated from normal and tumour cells

Kinetic parameters of spontaneous lipid peroxidation (LP) in the endoplasmic reticulum (ER) membranes isolated from the liver of healthy mice, tumour-host and ascitic Ehrlich tumour cells have been studied. The LP kinetics was characterized based on the primary LP products, dienic conjugates (DC), and the extent of lipid substrate unsaturation (double bond (DB) concentration per mg lipids). It was shown that the rate constants of the DC formation and DB consumption were, respectively, (6.3 +/- 0.7) . 10(-2) and(4.5 +/- 0.3) . 10(-2) min(-1) in the control; (2.5 +/- 0.3) . 10(-2) and (1.0 +/- 0,1) . . 10(-2) min(-1) in the ER from the tumour-host liver; (1.4 +/- 0.1) . 10(-2) and (0.38 +/- 0.01) . 10(-2) min(-1) in the ER from the tumour cells. The initial DC and DB levels in membranes of the tumour cells were significantly (by 2 and 3 times) lower than in the ER isolated from the control liver. There is a correlation between the DB initial level and the constants of DB consumption during LP in vitro for all the types of membranes studied.