Moreover, selleckchem to determine the activity of ACE in TGR(Tie2B1) rats, on the conversion of AngI to AngII, contractile responses induced by AngI pre-incubated for 30 min with lisinopril were tested. Concentration–response curves were obtained incubating non-cumulative concentrations of AngI to avoid desensitization. In the presence of ACE inhibitor there was similar inhibition of the responses throughout all tested concentrations
of the agonist in both strains of the rats (WT, 5C and TGR(Tie2B1), 5D). The pD2 values expressing the potency and the maximal response (Emax) values are presented in Table 1. The ACE activity was also determined using a selective fluorescence substrate assay for ACE with Abz-FRK(Dnp)P-OH as substrate. These results showed that the hydrolysis of the substrate was not different between WT and transgenic rat overexpressing the B1R (Fig. 6). It was found that the cleavage of this substrate was completely abolished by 0.5 μM lisinopril. The expression levels of B2R were determined by real time PCR relative quantification, since the maximum effect induced by
BK in the transgenic TGR(Tie2B1) rats was higher than in the WT rats. Furthermore, expression level of ACE was evaluated. Fig. 7 shows the results about the levels of their expression, which was calculated by fold-up change of the transgenic rat over the control group. The expression level http://www.selleckchem.com/screening/natural-product-library.html of B2R increased about three folds in the TGR(Tie2B1) rat whereas that of ACE mRNA expression
was not significantly different from the control WT rats. Responsiveness of the thoracic aortic rings to angiotensin II (AngII) induced contractile response was assessed to evaluate any cross-talking between kinin and AT1 receptors under conditions where the expression level of B2R was shown to be increased in TGR(Tie2B1) rat. The concentration-responses curves were obtained using non-cumulative manner for stimulations to avoid desensitization. The data show that the vascular reactivity to AngII (Fig. 8) in the aortic rings from TGR(Tie2B1) rats was not altered when compared to that of WT rat. The maximal response Galactosylceramidase values (%) were 31 ± 4 (4) for WT and 30 ± 2 (5) for TGR(Tie2B1) and the pD2 values were 7.8 ± 0.2 (4) for WT and 7.9 ± 0.2 (5) for TGR(Tie2B1). In addition, the determination of AT1 receptor mRNA expression revealed that in aorta overexpressing the B1 and B2 receptors, there was no significant difference from the control WT rats (Fig. 7). The present study showed that the vascular reactivity to BK as well as the expression level of B2R mRNA were increased in rats overexpressing the kinin B1R (TGR(Tie2B1)) exclusively in the endothelium. The relaxation of aortic rings induced by BK was significantly greater in this transgenic rat than the control, which was completely abolished by B2R antagonist HOE-140.