AIMTo investigate the role and mechanism of the bradykinin(BK) B1 receptor in the antiproliferative effects of the angiotensin-converting enzyme inhibitor (ACEI) captopril on rat cardiac fibroblasts (CFs) treated with angiotensin II (Ang II).

METHODSNeonatal rat cardiac fibroblasts were randomly treated with Ang II, captopril, B2 receptor antagonist (icatibant) or B1 receptor antagonist (des-Arg10, Leu9-kallidin). Thiazolyl blue (MTT) and flow cytometry (FCM) were used to evaluate cell number and cell cycle, respectively. Nitric oxide (NO) and intracellular cGMP level were measured by colorimetry and radioimmunoassay.

RESULTSAfter incubating the fibroblasts with 10(-7) mol/L Ang II for 48 hours, the percentage of CFs in the S stage and the value of MTT A490 nm were significantly increased (P < 0.01 vs control), and this increase was inhibited by 10(-5) mol/L captopril; however, NO and cGMP level were significantly higher than with Ang II alone (P < 0.01). 10(-5) mol/L icatibant attenuated the effects of captopril, which were blunted further by dual blockade of both B1 and B12.

CONCLUSIONActing via the B2 receptor, BK contributes to the antiproliferative effects of ACEI on CFs. In the absence of the B2 receptor, the B1 receptor may assume some of the functions of the B2 receptor and contribute to inhibition of CFs proliferation by ACEI.

Animals ; Bradykinin B1 Receptor Antagonists ; pharmacology ; Captopril ; pharmacology ; Cell Proliferation ; drug effects ; Heart Ventricles ; Myocytes, Cardiac ; cytology ; Rats ; Rats, Sprague-Dawley ; Receptor, Bradykinin B1 ; metabolism

OBJECTIVETo study the expression of bradykinin and its receptors B1R and B2R in the kidney immune injury in trichloroethylene-sensitized mouse and discuss the pathogenesis of Dermatitis Medicamentosa-like of TCE (ODMLT).

METHODSOn the first days, intradermal injection by 50% TCE and the amount of FCA mixture 100 µl for initial sensitization; on 4, 7, 10 days, painted abdominal skin by 100 µl 50% TCE for three sensitization, on 17, 19 days, painted on the back skin by 100 µl 30% TCE for initial excitation and the last challenge; 24 h before each challenge, PKSI-527+TCE group received intraperitoneal injection by inhibitor PKSI-527 (50 mg/kg); solvent control group treat without TCE and sensitization and excitation reagent the same proportion of olive oil and acetone mixture, blank control group without any treatment. Before killing the mouse, renal weight and body weight were recorded. The renals and plasma were separated at 24 h, 48 h, 72 h and 7 d after the last challenge and observed pathological of the renals. Expression of B1R and B2R in renal were examined by immunofluorescence technique. Plasma were examined by ELISA for BK.

RESULTSThe renal pathological examination revealed the apparent damage of TCE sensitized mice which compared to solvent control group showed obvious cellular infiltration, vacuolar degeneration of renal tubular epithelial cells. The renal damage of PKSI-527+TCE-sensitized groups which compared to the corresponding point of TCE-sensitized groups showed significantly reduced. The expression of BK in 24 h, 48 h and 72 h TCE-sensitized groups were significant higher than solvent control group and related TCE non-sensitized groups (P < 0.05) and 72 h point compared to the corresponding point of PKSI-527+TCE group was also increased, the difference was statistically significant (P < 0.05). The expression levels of B1R and B2R in the kidney in 24 h, 48 h, 72 h and 7 d TCE-sensitized groups were obviously higher than solvent control group and related TCE non-sensitized groups. The expression levels of B1R and B2R in the kidney in the four point of PKSI-527+TCE sensitized group were relatively lower than the corresponding point of TCE sensitized group.

CONCLUSIONKKS activation may involved in the renal immune injury of trichloroethylene-sensitized mouse and the expression change of bradykinin and its receptors B1R and B2R which may play an important role in the process.

Administration, Cutaneous ; Animals ; Bradykinin ; metabolism ; Kidney ; drug effects ; metabolism ; pathology ; Mice ; Phenylalanine ; analogs & derivatives ; Receptor, Bradykinin B1 ; metabolism ; Receptor, Bradykinin B2 ; metabolism ; Solvents ; Tranexamic Acid ; analogs & derivatives ; Trichloroethylene ; toxicity

BACKGROUNDBradykinin (BK) acts mainly on two receptor subtypes: B(1) and B(2), and activation of B(2) receptor mediates the most well-known cardioprotective effects of angiotensin converting enzyme inhibitors (ACEi), however, the role that B(1) receptor plays in ACEi has not been fully defined. We examined the role of B(1) receptor in the inhibitory effect of ACE inhibitor captopril on rat cardiomyocyte hypertrophy and cardiac fibroblast proliferation induced by angiotensin II (Ang II) and explored its possible mechanism.

METHODSNeonatal cardiomyocytes and cardiac fibroblasts (CFs) were randomly treated with Ang II, captopril, B(2) receptor antagonist (HOE-140) and B(1) receptor antagonist (des-Arg(10), Leu(9)-kallidin) alone or in combination. Flow cytometry was used to evaluate cell cycle, size and protein content. Nitric oxide (NO) and intracellular cyclic guanosine monophosphate (cGMP) level were measured by colorimetry and radioimmunoassay.

RESULTSAfter the CFs and cardiomyocytes were incubated with 0.1 micromol/L Ang II for 48 hours, the percentage of CFs in the S stage, cardiomyocytes size and protein content significantly increased (both P < 0.01 vs control), and these increases were inhibited by 10 micromol/L captopril. However, NO and cGMP levels were significantly higher than that with Ang II alone (both P < 0.01). 1 micromol/L HOE-140 or 0.1 micromol/L des-Arg(10), Leu(9)-kallidin attenuated the effects of captopril, which was blunted further by blockade of both B(1) and B(2) receptors.

CONCLUSIONSActing via B(2) receptor, BK contributes to the antihypertrophic and antiproliferative effects of captopril on cardiomyocytes and CFs. In the absence of B(2) receptor, B(1) receptor may act a compensatory mechanism for the B(2) receptor and contribute to the inhibition of cardiomyocyte hypertrophy and CFs proliferation by captopril. NO and cGMP play an important role in the effect of B(1) receptor.

Angiotensin-Converting Enzyme Inhibitors ; pharmacology ; Animals ; Animals, Newborn ; Captopril ; pharmacology ; Cardiomegaly ; prevention & control ; Cell Proliferation ; drug effects ; Cell Size ; drug effects ; Cyclic GMP ; analysis ; DNA ; biosynthesis ; Fibroblasts ; drug effects ; physiology ; Myocytes, Cardiac ; drug effects ; pathology ; Nitric Oxide ; analysis ; Rats ; Rats, Sprague-Dawley ; Receptor, Bradykinin B1 ; physiology