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

Kallidinogenase normalizes retinal vasopermeability in streptozotocin-induced diabetic rats: potential roles of vascular endothelial growth factor and nitric oxide

We studied the suppressant effect of kallidinogenase on retinal vascular permeability and vascular endothelial growth factor (VEGF) in diabetic rats. Diabetes was induced by intravenously injecting streptozotocin (60 mg/kg body weight) dissolved in citrate buffer. Kallidinogenase (7 microg/kg/day) was injected intravenously once daily for 21 days. The retinal vascular permeability was estimated from the amount of fluorescent dye leaking into the retina after administration of fluorescein isothiocyanate-conjugated dextran. VEGF in intraocular fluids was quantified by an enzyme-linked immunosorbent assay. The amounts of nitrite and nitrate in the retina were quantified by a fluorescence method using 2,3-diaminonaphthalene. Retinal vascular permeability in the diabetic control group was about 5.5 times higher than in the normal control group (P<0.001). Kallidinogenase suppressed the increased retinal vascular permeability. In the diabetic control group, the VEGF level was three times that of the normal control group (diabetic control group, 160+/-12 pg/ml; normal control group, 54+/-9 pg/ml; P<0.001). The VEGF concentration in the kallidinogenase-treated group was 120+/-12 pg/ml (P<0.05). In the diabetic control group, the amounts of nitrite and nitrate in the retina were lower by about 2.6-fold, compared with the normal control group (P<0.05). Kallidinogenase almost normalized the decreases in nitrite and nitrate in the retina. The current study showed beneficial effects of kallidinogenase on increased retinal vascular permeability and VEGF in diabetic rats, suggesting that kallidinogenase may be effective for simple retinopathy in patients with diabetes.

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.

Does the kinin system mediate in cardiovascular abnormalities? An overview

All the components of the kallikrein-kinin system are located in the cardiac muscle, and its deficiency may lead to cardiac dysfunction. In recent years, numerous observations obtained from clinical and experimental models of diabetes, hypertension, cardiac failure, ischemia, myocardial infarction, and left ventricular hypertrophy have suggested that the reduced activity of the local kallikrein-kinin system may be instrumental for the induction of cardiovascular-related diseases. The cardioprotective property of the angiotensin-converting enzyme inhibitors is primarily mediated via the kinin-releasing pathway, which may cause regression of left ventricular hypertrophy in hypertensive situations. The ability of kallikrein gene delivery to produce a wide spectrum of beneficial effects makes it an excellent candidate in treating hypertension and cardiovascular and renal diseases. In addition, stable kinin agonists may also be available in the future as therapeutic agents for cardiovascular and renal disorders.