Depolarization of mitochondria in endothelial cells promotes cerebral artery vasodilation by activation of nitric oxide synthase
| Autor: | Adam Institoris, Prasad V. G. Katakam, Ibolya Rutkai, James A. Snipes, David W. Busija, Tamas Gaspar, Ferenc Domoki, Edina A Wappler, Samuel M. Grovenburg, Paige S. Katz |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
Potassium Channels
Vasodilator Agents Vasodilation Mitochondrion Rats Sprague-Dawley chemistry.chemical_compound Enos Enzyme Inhibitors Phosphorylation Cells Cultured Phosphoinositide-3 Kinase Inhibitors Membrane Potential Mitochondrial biology Imidazoles Nitric Oxide Synthase Type III Depolarization Free Radical Scavengers Mitochondria Nitric oxide synthase Cerebrovascular Circulation Cardiology and Cardiovascular Medicine medicine.drug Signal Transduction medicine.medical_specialty Blotting Western Nitric Oxide Article Nitric oxide Internal medicine medicine Diazoxide Potassium Channel Blockers Animals Benzopyrans Dose-Response Relationship Drug Electron Spin Resonance Spectroscopy Endothelial Cells Cerebral Arteries biology.organism_classification Rats Enzyme Activation Endocrinology chemistry biology.protein Calcium Phosphatidylinositol 3-Kinase Reactive Oxygen Species Proto-Oncogene Proteins c-akt |
| Zdroj: | Arteriosclerosis, thrombosis, and vascular biology. 33(4) |
| ISSN: | 1524-4636 |
| Popis: | Objective— Mitochondrial depolarization after ATP-sensitive potassium channel activation has been shown to induce cerebral vasodilation by the generation of calcium sparks in smooth muscle. It is unclear, however, whether mitochondrial depolarization in endothelial cells is capable of promoting vasodilation by releasing vasoactive factors. Therefore, we studied the effect of endothelial mitochondrial depolarization by mitochondrial ATP-sensitive potassium channel activators, BMS-191095 (BMS) and diazoxide, on endothelium-dependent vasodilation. Approach and Results— Diameter studies in isolated rat cerebral arteries showed BMS- and diazoxide-induced vasodilations that were diminished by endothelial denudation. Mitochondrial depolarization-induced vasodilation was reduced by inhibition of mitochondrial ATP-sensitive potassium channels, phosphoinositide-3 kinase, or nitric oxide synthase. Scavenging of reactive oxygen species, however, diminished vasodilation induced by diazoxide, but not by BMS. Fluorescence studies in cultured rat brain microvascular endothelial cells showed that BMS elicited mitochondrial depolarization and enhanced nitric oxide production; diazoxide exhibited largely similar effects, but unlike BMS, increased mitochondrial reactive oxygen species production. Measurements of intracellular calcium ([Ca 2+ ] i ) in cultured rat brain microvascular endothelial cells and arteries showed that both diazoxide and BMS increased endothelial [Ca 2+ ] i . Western blot analyses revealed increased phosphorylation of protein kinase B and endothelial nitric oxide synthase (eNOS) by BMS and diazoxide. Increased phosphorylation of eNOS by diazoxide was abolished by phosphoinositide-3 kinase inhibition. Electron spin resonance spectroscopy confirmed vascular nitric oxide generation in response to diazoxide and BMS. Conclusions— Pharmacological depolarization of endothelial mitochondria promotes activation of eNOS by dual pathways involving increased [Ca 2+ ] i as well as by phosphoinositide-3 kinase-protein kinase B–induced eNOS phosphorylation. Both mitochondrial reactive oxygen species–dependent and –independent mechanisms mediate activation of eNOS by endothelial mitochondrial depolarization. |
| Databáze: | OpenAIRE |
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