Vascular Kinin B and B Receptors Determine Endothelial Dysfunction through Neuronal Nitric Oxide Synthase.

B- and B-kinin receptors are G protein-coupled receptors that play an important role in the vascular function. Therefore, the present study was designed to evaluate the participation of kinin receptors in the acetylcholine (ACh)-induced vascular relaxation, focusing on the protein-protein interaction involving kinin receptors with endothelial and neuronal nitric oxide synthases (eNOS and nNOS). Vascular reactivity, nitric oxide (NO·) and reactive oxygen species (ROS) generation, co-immunoprecipitation were assessed in thoracic aorta from male wild-type (WT), B- (BR), B- (BR) knockout mice. Some vascular reactivity experiments were also performed in a double kinin receptors knockout mice (BBR). For pharmacological studies, selective B- and B-kinin receptors antagonists, NOS inhibitors and superoxide dismutase (SOD) mimetic were used. First, we show that B- and B-kinin receptors form heteromers with nNOS and eNOS in thoracic aorta. To investigate the functionality of these protein-protein interactions, we took advantage of pharmacological tools and knockout mice. Importantly, our results show that kinin receptors regulate ACh-induced relaxation via nNOS signaling in thoracic aorta with no changes in NO· donor-induced relaxation. Interestingly, BBR presented similar level of vascular dysfunction as found in BR or BR mice. In accordance, aortic rings from BR or BR mice exhibit decreased NO· bioavailability and increased superoxide generation compared to WT mice, suggesting the involvement of excessive ROS generation in the endothelial dysfunction of BR and BR mice. Alongside, we show that impaired endothelial vasorelaxation induced by ACh in BR or BR mice was rescued by the SOD mimetic compound. Taken together, our findings show that B- and B-kinin receptors regulate the endothelium-dependent vasodilation of ACh through nNOS activity and indicate that molecular disturbance of short-range interaction between B- and B-kinin receptors with nNOS might be involved in the oxidative pathogenesis of endothelial dysfunction.