The effect of bradykinin and its antagonist on survival time after coronary artery occlusion in hypertensive rats

It is known that BK does play a role in the cardioprotective effect of angi otensin converting enzyme (ACE) inhibitors. The present study therefore was conducted to examine the effects of bradykinin (BK) and its antagonist on survival time in spontaneously hypertensive rats (SHR) with coronary artery ligation for 15 min and continuously. We also evaluated the heart rate and blood pressure (BP) in the presence and absence of BK and BK2 receptor ant agonist, D-Arg-[Hyp-D-Phe(7)]BK. Coronary artery was Ligated in anaesthetiz ed rats and they were artificially ventilated with room air (stroke volume, 4 ml; 48 strokes/min) as described by the previous investigators. Lead II elecrocardiogram (ECG) was recorded from subcutaneous steel needle electrod es. Results of this investigation indicated that BK treatment 4 mu g/kg (i. v.) and 8 mu g/kg (i.v.) caused significant (P < 0.05) increase in survival time in SHR with coronary artery ligation for 15 min and continuously as c ompare to their respective saline-treated controls. However, BK antagonist treatment 4 mu g/kg (i.v.) abolished the increase in survival time caused b y BK treatment. The mean values of survival time between the saline-treated and BK antagonist plus BK-treated rats did not differ significantly (P > 0 .05). The heart rate and BP responses were greatly reduced (P < 0.001) in t he presence of coronary artery ligation. These findings suggest that BK mig ht have cardioprotective effect to increase the survival time in rats by ac tivating BK, receptors after coronary artery ligation. (C) 1999 Published b y Elsevier Science B.V. All rights reserved.