Journal of cardiovascular pharmacology
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J. Cardiovasc. Pharmacol. · Oct 1997
Effects of bradykinin and icatibant on renal hemodynamics in conscious spontaneously hypertensive and normotensive rats.
We investigated the effects of bradykinin (BK) and icatibant (HOE 140), a highly selective bradykinin-B2-receptor antagonist, on mean arterial blood pressure (MAP), heart rate (HR), renal blood flow (RBF), and renal vascular resistance (RVR) in conscious Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). Experiments were performed in conscious male WKY rats and SHRs instrumented over the long term with arterial and venous catheters and a transit-time flow probe for measurement of RBF. In WKY rats (n = 16), intraaortic (i.a.) bolus injections of BK (0.1, 1.0, and 10 microg) produced dose-dependent decreases in MAP and RBF with reciprocal increases in RVR. ⋯ Our results provide evidence that BK exhibits renal vasoconstrictor and vasodilator properties in vivo, both mediated by B2-receptors. Furthermore, we demonstrated that SHRs display an increased B2-receptor-mediated vasodilatory responsiveness to BK. Finally we showed that blockade of B2 receptors leads to an increase of MAP in SHRs in contrast to WKY rats, suggesting an important role of the kallikrein/kinin system in the regulation of high blood pressure in SHRs.