Angiotensin 1-7 induces bradykinin-mediated relaxation in porcine coronary artery

作者：Gorelik G; Carbini LA; Scicli AG^*

来源：Journal of Pharmacology and Experimental Therapeutics, 1998, 286(1): 403-410.

Angiotensin 1-7 (Ang 1-7) has been reported to induce relaxation which is partially blocked by a kinin receptor antagonist. We investigated the relationship between kinins and angiotensin peptides with use of preconstricted isolated pig coronary arteries. Ang 1-7 alone (up to 10(-5) M) had no relaxant effect. Bradykinin (BK) (10(-10)-10(-7) M) induced transient relaxation, returning to basal tone, although BK remained in the bath. in these BK-stimulated rings, Ang 1-7 but not BK (both 5 x 10(-6) M) again relaxed the rings by approximately 50%. This relaxation was blocked by a BK B(2) antagonist, a kininase, and a nitric oxide synthase inhibitor. Ang 1-7 inhibited purified angiotensin-converting enzyme (ACE) by 30 +/- 3.5% (n = 4) at 10(-6) M. However, in BK-pretreated rings, the ACE inhibitor ramiprilat did not induce relaxation, nor did it affect the relaxant response to Ang 1-7, which suggests that the effect of Ang 1-7 was not caused by ACE inhibition. Ang 1-7-induced vasodilation was reduced by 69.9 +/- 6.2% by an AT(2) receptor blocker, PD-123319, and 29.3 +/- 7.3% by an AT(1) antagonist, losartan. Neither the nonselective AT(1)/AT(2) receptor antagonist sarthran nor saralasin inhibited the response to Ang 1-7. Ang II did not elicit relaxation either alone or in the presence of losartan, which suggests that activation of AT(2) receptors does not cause relaxation. Thus, in the presence of bradykinin, Ang 1-7 relaxes pig coronary arteries via a PD-123319-sensitive mechanism involving nitric oxide, kinins and the BK B(2) receptor. The kallikrein-kinin and renin-angiotensin systems may be linked through the interaction of Ang 1-7 and BK.

• 出版日期1998-7