The effect of bradykinin on the oxidative state of rats with acute hyperglycaemia

Many clinical and experimental studies have established the beneficial effect of kinins in hypertension, heart failure and ischaemia-reperfusion syndrome, but little attention has been given to the role of kinins in hyperglycaemic conditions. The purpose of the present study was to determine the influence of bradykinin on the levels of glucose, insulin, malondialdehyde and hydrogen peroxide, as well as antioxidative enzyme activity in rats with streptozotocin (STZ)-induced acute hyperglycaemia. In STZ-induced hyperglycaemic rats the levels of glucose, hydrogen peroxide and malondialdehyde were increased by 256% (from 6.0 +/- 0.3 to 21.4 +/- 1.3 mmol/l, P < 0.001), 33% (from 1.9 +/- 0.1 to 5.6 +/- 0.3 mmol H2O2/ml, P < 0.001) and 19% (from 3.7 +/- 0.3 to 4.9 +/- 0.2 nmol/l, P < 0.001) respectively. The activity of superoxide dismutase, catalase and glutathione peroxidase and the level of insulin were decreased by 46% (from 1367 +/- 73 to 737 +/- 59 U/g Hb, P < 0.001), 36% (from 2.3 +/- 0.3 to 1.4 +/- 0.1 U Bergmayera/g Hb, P < 0.001), 31% (from 236 +/- 19 to 163 +/- 24 U/g Hb, P < 0.001) and 91% (from 47.5 +/- 1.7 to 2.4 +/- 0.5 mU/1, P < 0.001) respectively in rats treated with streptozotocin. The administration of bradykinin caused the decrease in glucose, hydrogen peroxide and malondi-aldehyde levels by 38% (from 21.4 +/- 1.3 to 13.3 +/- 1.0 mmol/l, P < 0.901), 37% (from 5.6 +/- 0.3 to 4.3 +/- 0.2 mmol H2O2/ml, P < 0.001), 39% (from 4.9 +/- 0.2 to 3.0 +/- 0.2 nmol/l, P < 0.001) respectively and the increase in insulin level and superoxide dismutase, catalase and glutathione peroxidase activity by 62% (from 2.4 +/- 0.5 to 4.0 +/- 0.4 mU/l, P +/- 0.001), 23% (from 736.8 +/- 58.5 to 906.7 +/- 47.8 U/g Hb, P < 0.001), 23% (from 1.4 +/- 0.1 to 1.9 +/- 0.1 U Bergmayera/g Hb, P < 0.01) and 19% (from 163.1 +/- 23.6 to 202.3 +/- 11.7 U/g Hb, P < 0.001) respectively in rats with hyperglycaemia. Thus, bradykinin is able to reduce oxidative stress in hyperglycaemic conditions. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.