Central nervous system kinin receptors and the hypertensive response mediated by bradykinin

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Abstract
1 Bradykinin (Bk) administered intracerebroventricularly to the rat causes an increase in arterial pressure. 2 Analogues of Bk with agonist and antagonist activity were injected, over a wide dose-range, into the posterior region of the fourth ventricle of unanaesthetized rats implanted with permanent ventricular canullae, and blood pressure was measured directly from the abdominal aorta. 3 The analogues Ile-Ser-Bk (T-kinin) and Lys-Lys-Bk, which interact with both B1 and B2 Bk receptors, produced pressor effects similar to those of Bk, although of greater duration, whereas des-Arg9-Bk, a B1 -receptor agonist, had no effect. 4 The B1-antagonist des-Arg9-[Leu8]-Bk did not alter the Bk pressor response, but D-Arg-[Hyp3, Thi5,8,D-Phe7]-Bk, which interacts both with B1- and B2-receptors blocked the responses to Bk, T-kinin and Lys-Lys-Bk and caused parallel shifts to the right of the Bk dose-response curves. Neither antagonist, by itself, had any effect on blood pressure. 5 It is concluded that the central pressor response to Bk is mediated by receptors of the B2 subtype.