title: Myoglobin facilitates angiotensin II-induced constriction of renal afferent arterioles.
abstract: Vasoconstriction plays an important role in the development of acute kidney injury in rhabdomyolysis. We hypothesized that myoglobin enhances the angiotensin II (ANG II) response in afferent arterioles by increasing superoxide and reducing nitric oxide (NO) bioavailability. Afferent arterioles of C57Bl6 mice were isolated perfused, and vasoreactivity was analyzed using video microscopy. NO bioavailability, superoxide concentration in the vessel wall, and changes in cytosolic calcium were measured using fluorescence techniques. Myoglobin treatment (10-5M) did not change the basal arteriolar diameter during a 20-min period compared with control conditions.NG-nitro-l-arginine methyl ester (l-NAME, 10-4M) and l-NAME + myoglobin reduced diameters to 94.7 and 97.9% of the initial diameter, respectively. Myoglobin or l-NAME enhanced the ANG II-induced constriction of arterioles compared with control (36.6 and 34.2%, respectively, vs. 65.9%). Norepinephrine responses were not influenced by myoglobin. Combined application of myoglobin and l-NAME further facilitated the ANG II response (7.0%). Myoglobin or l-NAME decreased the NO-related fluorescence in arterioles similarly. Myoglobin enhanced the superoxide-related fluorescence, and tempol prevented this enhancement. Tempol also partly prevented the myoglobin effect on the ANG II response. Myoglobin increased the fura 2 fluorescence ratio (cytosolic calcium) during ANG II application (10-12to 10-6M). The results suggest that the enhanced afferent arteriolar reactivity to ANG II is mainly due to a myoglobin-induced increase in superoxide and associated reduction in the NO bioavailability. Signaling pathways for the augmented ANG II response include enhanced cytosolic calcium transients. In conclusion, myoglobin may contribute to the afferent arteriolar vasoconstriction in this rhabdomyolysis model.
authors.affiliation: Institute of Vegetative Physiology, Berlin, Germany.
authors.forename: Z Z
authors.initials: ZZ
authors.lastname: Liu
authors.affiliation: Department of Nephrology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Mathia
authors.affiliation: Institute of Vegetative Physiology, Berlin, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Pahlitzsch
authors.affiliation: Institute of Vegetative Physiology, Berlin, Germany.
authors.forename: I C
authors.initials: IC
authors.lastname: Wennysia
authors.affiliation: Institute of Vegetative Physiology, Berlin, Germany.
authors.forename: P B
authors.initials: PB
authors.lastname: Persson
authors.affiliation: Department of Physiology, Zhejiang University School of Medicine, Hangzhou, China; and.
authors.forename: E Y
authors.initials: EY
authors.lastname: Lai
authors.affiliation: Institute of Vegetative Physiology, Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Högner
authors.affiliation: Institute of Vegetative Physiology, Berlin, Germany.
authors.forename: M Z
authors.initials: MZ
authors.lastname: Xu
authors.affiliation: Medical Faculty Mannheim, Research Division Cardiovascular Physiology, Centre for Biomedicine and Medical Technology Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Schubert
authors.affiliation: Department of Nephrology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Rosenberger
authors.affiliation: Institute of Vegetative Physiology, Berlin, Germany; andreas.patzak@charite.de.
authors.forename: A
authors.initials: A
authors.lastname: Patzak
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001160:Arterioles / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D020013:Calcium Signaling / Q000187:drug effects; D003497:Cyclic N-Oxides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007668:Kidney / Q000098:blood supply*; D008297:Male; D008810:Mice, Inbred C57BL; D018715:Microscopy, Video; D009211:Myoglobin / Q000494:pharmacology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D012206:Rhabdomyolysis / Q000378:metabolism / Q000503:physiopathology*; D013113:Spin Labels; D013481:Superoxides / Q000378:metabolism; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D003497:Cyclic N-Oxides; D004791:Enzyme Inhibitors; D009211:Myoglobin; D013113:Spin Labels; D014662:Vasoconstrictor Agents; D013481:Superoxides; D000804:Angiotensin II; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; C001803:tempol; D019331:NG-Nitroarginine Methyl Ester
keywords: acute kidney injury; calcium; nitric oxide; rhabdomyolysis