title: Heme oxygenase attenuates angiotensin II-mediated superoxide production in cultured mouse thick ascending loop of Henle cells.
abstract: Heme oxygenase (HO)-1 induction can attenuate the development of angiotensin II (ANG II)-dependent hypertension. However, the mechanism by which HO-1 lowers blood pressure is not clear. The goal of this study was to test the hypothesis that induction of HO-1 can reduce the ANG II-mediated increase in superoxide production in cultured thick ascending loop of Henle (TALH) cells. Studies were performed on an immortalized cell line of mouse TALH (mTALH) cells. HO-1 was induced in cultured mTALH cells by treatment with cobalt protoporphyrin (CoPP, 10 microM) or hemin (50 microM) or by transfection with a plasmid containing the human HO-1 isoform. Treatment of mTALH cells with 10(-9) M ANG II increased dihydroethidium (DHE) fluorescence (an index of superoxide levels) from 35.5+/-5 to 136+/-18 relative fluorescence units (RFU)/microm2. Induction of HO-1 via CoPP, hemin, or overexpression of the human HO-1 isoform significantly reduced ANG II-induced DHE fluorescence to 64+/-5, 64+/-8, and 41+/-4 RFU/microm2, respectively. To determine which metabolite of HO-1 is responsible for reducing ANG II-mediated increases in superoxide production in mTALH cells, cells were preincubated with bilirubin or carbon monoxide (CO)-releasing molecule (CORM)-A1 (each at 100 microM) before exposure to ANG II. DHE fluorescence averaged 80+/-7 RFU/microm2 after incubation with ANG II and was significantly decreased to 55+/-7 and 53+/-4 RFU/microm2 after pretreatment with bilirubin and CORM-A1. These results demonstrate that induction of HO-1 in mTALH cells reduces the levels of ANG II-mediated superoxide production through the production of both bilirubin and CO.
authors.affiliation: Department of Physiology & Biophysics, University of Mississippi Medical Center, Jackson, MS 39216, USA.
authors.forename: Silvia
authors.initials: S
authors.lastname: Kelsen
authors.forename: Bijal J
authors.initials: BJ
authors.lastname: Patel
authors.forename: Lawson B
authors.initials: LB
authors.lastname: Parker
authors.forename: Trinity
authors.initials: T
authors.lastname: Vera
authors.forename: John M
authors.initials: JM
authors.lastname: Rimoldi
authors.forename: Rama S V
authors.initials: RS
authors.lastname: Gadepalli
authors.forename: Heather A
authors.initials: HA
authors.lastname: Drummond
authors.forename: David E
authors.initials: DE
authors.lastname: Stec
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001663:Bilirubin / Q000378:metabolism / Q000494:pharmacology; D002248:Carbon Monoxide / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D006162:Guanylate Cyclase / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism*; D006427:Hemin / Q000378:metabolism / Q000494:pharmacology; D008138:Loop of Henle / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D011524:Protoporphyrins / Q000378:metabolism / Q000494:pharmacology; D034741:RNA, Small Interfering; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D000071756:Soluble Guanylyl Cyclase; D013481:Superoxides / Q000378:metabolism*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D011524:Protoporphyrins; D034741:RNA, Small Interfering; D018160:Receptors, Cytoplasmic and Nuclear; D014662:Vasoconstrictor Agents; D013481:Superoxides; D000804:Angiotensin II; C007095:cobaltiprotoporphyrin; D006427:Hemin; D002248:Carbon Monoxide; D051547:Heme Oxygenase-1; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase; D001663:Bilirubin