The kallikrein-kinin system: from mediator of inflammation to modulator of cardioprotection

Kinin is an important mediator of hyperalgesia, inflammatory conditions and asthma. It causes pain, inflammation, increased vascular permeability and vasodilatation. Several kinin antagonists have been developed with the aim of treating these pathologies. Kinin B2 receptor agonists and kallikrein may have clinical utility in the treatment of hypertension, left ventricular hypertrophy, ischemic heart disease, congestive heart failure and diabetes. However, there is a need to know whether there is a safe therapeutic window between potential cardio-protective and pro-inflammatory effects following administration of kinin B2 receptor agonists.

Tissue kallikrein increases duration of survival after prolonged coronary artery ligation in hypertensive rats

There is evidence that the kallikrein-kinin system (KKS) is an important mediator in the regulation of blood pressure, and cardiac and renal hemodynamics. The present study was designed to examine the effect of tissue kallikrein and Trasylol, an inhibitor of tissue kallikrein, on survival time after continuous (prolonged) coronary artery ligation in spontaneously hypertensive rats (SHR). Tissue kallikrein (8 and 16 microg/kg, i.v.) treatment caused significant (p < 0.05) increases in the survival time of SHR as compared with the saline-treated control SHR. Trasylol pretreatment abolished (p < 0.05) the beneficial effect of tissue kallikrein on survival time. The tissue kallikrein treatment resulted in a significant (p < 0.05) reduction in systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) of SHR as compared to the saline-treated control SHR. Trasylol (6 microg/kg) treatment antagonized the effects of tissue kallikrein associated with survival time, SBP, DBP and HR. Ligation of the coronary artery caused a significant (p < 0.001) reduction in the SBP, DBP and HR of SHR, when the mean values were compared between before coronary artery ligation and after coronary artery ligation. However, there was no significant difference (p > 0.05) in SBP, DBP and HR between saline and kallikrein-treated SHR after coronary artery ligation. These findings may suggest that tissue kallikrein is able to act as a cardioprotective agent as demonstrated by an increase in survival time of SHR with prolonged coronary artery ligation.

Evaluation of tissue kallikrein activity on survival time after acute coronary artery ligation in hypertensive rats

It is known that the tissue kallikrein-kinin system is located in the cardiac tissue, and the lack of this system in the cardiac tissue might induce cardiac dysfunctions. In this study, we investigated the potential role of tissue kallikrein and Trasylol, an inhibitor of tissue kallikrein, on survival time with acute left coronary artery ligation for 15 min in spontaneously hypertensive rats (SHR). Tissue kallikrein (8 and 16 microg/kg, i.v.) treatment caused significant (P<0.05) increases in the survival time of SHR as compared with the saline-treated control SHR. Trasylol pretreatment abolished (P<0.05) the beneficial effect on tissue kallikrein on survival time. The ligation of coronary artery resulted in significant (P<0.05) reduction in systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) of SHR compared with the saline-treated control SHR. The tissue kallikrein treatment caused greater (P<0.001) reduction in the SBP, DBP and HR of SHR, when the mean values were compared between before coronary artery ligation and after coronary artery ligation. Trasylol (6 microg/kg) treatment antagonized the effects of tissue kallikrein associated with survival time, SBP, DBP and HR. These findings may suggest that tissue kallikrein is able to act as a cardioprotective agent as demonstrated by the increase in survival time of SHR with acute coronary artery ligation. The significance of these observations is discussed.