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- Title
Epoxygenase Metabolites Contribute to Nitric Oxide-Independent Afferent Arteriolar Vasodilation in Response to Bradykinin.
- Authors
Imig, John D.; Falck, John R.; Shouzou Wei, John R.; Capdevila, Jorge H.
- Abstract
In the kidney, epoxyeicosatrienoic acids (EETs) have been suggested to be endothelium-derived hyperpolarizing factors (EDHFs). The aim of the present study was to determine the contribution of EETs to the preglomerular vasodilation elicited by bradykinin. Sprague-Dawley rats were studied utilizing an in vitro perfused juxtamedullary nephron preparation. The afferent arteriolar diameter was determined and the diameter averaged 19 ± 1 μm (n = 26) at a renal perfusion pressure of 100 mm Hg. Addition of 1, 10 and 100 nM bradykinin to the perfusate dose-dependently increased afferent arteriolar diameter by 5 ± 1, 12 ± 2 and 17 ± 2%, respectively. The nitric oxide inhibitor N[sup ω] -nitro-L-arginine reduced bradykinin-induced afferent arteriolar vasodilation by 50%, and the diameter increased by 9 ± 2% in response to 100 nM bradykinin. Epoxygenase inhibitors N-methylsulphonyl-6-(2-propargyloxyphenyl)hexanamide or miconazole greatly attenuated the nitric oxide-independent component of the vasodilation elicited by bradykinin. Cyclooxygenase (COX) inhibition attenuated the nitric oxide-independent vasodilation elicited by 1 nM bradykinin but did not significantly affect the vascular response to 100 nM bradykinin. Combined inhibition of nitric oxide, COX and epoxygenase pathways completely abolished bradykinin-mediated afferent arteriolar vasodilation. In additional studies, renal microvessels were isolated and incubated with bradykinin and samples were analyzed by NICI/GC/MS. Under control conditions, renal microvascular EET levels averaged 49 ± 9 pg/mg/20 min (n = 7). In the presence of bradykinin, EET levels were significantly higher and averaged 81 ± 11 pg/mg/20 min (n = 7). These data support the concept that EETs are EDHFs and contribute to the nitric oxide-independent afferent arteriolar vasodilation elicited by bradykinin.Copyright © 2001 S. Karger AG, Basel
- Subjects
METABOLITES; NITRIC oxide; VASODILATION; BRADYKININ; CYTOCHROME P-450
- Publication
Journal of Vascular Research, 2001, Vol 38, Issue 3, p247
- ISSN
1018-1172
- Publication type
Article
- DOI
10.1159/000051053