Pharmacology of kinins in the arterial and venous mesenteric bed of normal and B2 knockout transgenic mice.

Abstract We have tested the vasoactive effects of kinins in addition to various other endothelium-dependent or independent agonists in the arterial and venous perfused mesenteric circuits of the mouse. Bradykinin (0.1 pmol–100 nmol), but not des–Arg 9 –bradykinin (10 nmol) induced a dose-dependent vasodilation of the precontracted arterial and venous mesenteric vasculature of the mouse. Furthermore, acetylcholine (2.5 nmol) also induced a marked arterial vasodilation but was without effect on the venous side. Other endothelium-dependent vasodilators, such as platelet-activating factor (PAF) (1 nmol), tachykinin NK 1 selective agonist ([Sar 9 ,Met(O 2 ) 11 ]substance P) (0.5 nmol) and adenosine diphosphate (5 nmol), were without effect on either side of the mesenteric bed of the mouse. The bradykinin B 2 receptor selective antagonist (HOE 140) abolished the arterial and venous vasodilation induced by bradykinin without affecting that of acetylcholine or sodium nitroprusside. In addition, the bradykinin B 1 receptor antagonist des–Arg 9 –[Leu 8 ]bradykinin was without effect on the responses induced by bradykinin. A nitric oxide synthase inhibitor N ω -nitro- l -arginine methyl ester ( l -NAME) markedly reduced, whereas removal of the endothelium with 3-[3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS) abolished dilatation to bradykinin and acetylcholine (arterial side only) without affecting that induced by sodium nitroprusside in the mouse arterial and venous mesenteric circuits. In the same two circuits of transgenic B 2 knockout mice, the vasodilatory responses to bradykinin were absent, whereas the arterial circuit still responded to acetylcholine by a l -NAME-sensitive vasodilation. Our results suggest the exclusive contribution of B 2 receptors located on the endothelium in the vasodilatory effects of bradykinin in the arterial and venous mesenteric circuits of the mouse.