INTERRELATION BETWEEN OXIDATIVE CARBONYLATION OF PROTEINS AND LYSOSOMAL PROTEOLYSIS OF PLASMA IN EXPERIMENTALLY MODELLEDISCHEMIA AND ISCHEMIA-REPERFUSION

The aim is to analyze dependence of lysosomal cysteine proteolysis on the extent of oxidative modification of proteins in experimental modelling of ischemia and ischemiareperfusion. The research was conducted on laboratory animals – rats of Wistar line. Two experimental models were created – ischemia and reperfusion by compression of the abdominal aorta (the first group) with subsequent conditioning (the second group). Activity of lysosomal proteinases and the level of oxidatively modified proteins were determined in blood plasma in the following periods after surgical intervention: 1st, 3d, 5th, 7th days in both groups, respectively. For control plasma of intact animal was examined. Activity of lysosomal cysteine proteinases B, L in experimentally modeled ischemia and ischemiareperfusion was studied using spectrofluorimetric method according to Barrett &Kirschke. Oxidative modification of proteins was evaluated by determination of levels of carbonyl derivatives by method of R.V. Levine in E.E. Dubinina's modification. Integrated assessment of oxidative modification of plasma proteins wasgiven, namely: the area under the absorption spectrum curve of protein carbonylation products, shares of the primary and secondary markers of oxidative stress and reserve-adaptation potential were calculated. Statistical significance of differences between independent samples was analyzed by Mann- Whitney rank test (U-test). Equality of medians ofseveral samples was checked by Kruskal- Wallis test. Rank correlation was evaluated using Spearman's coefficient. The obtained results demonstrate development of oxidative stress from 1st to 7th day in ischemia-reperfusion and on the 3d and 5th day in ischemia,accompanied by activation of cathepsins B and L. In ischemia and ischemia-reperfusion depletion of reserve-adaptation potential was noted, with predomination of primary markers in ischemia and of secondary markers in reperfusion. Data analysis evidences a positive correlation between oxidative carbonylation of proteins and activity of plasma cathepsin L on the 3d, 5th day in ischemia and on the 3d day in ischemia-reperfusion.