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Increased Na transport in rat medullary thick ascending limb stimulates mitochondrial hydrogen peroxide production
Author(s) -
Ohsaki Yusuke,
Mori Takefumi,
Lu Yi,
Ito Sadayoshi,
Ryan Robert P.,
Dickinson Bryan C.,
Chang Christopher J.,
Cowley Allen W.
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.667.6
Increases of luminal flow and Na delivery are known to stimulate ROS production in the epithelial cells of the renal medullary thick ascending limb (mTAL) with increases of O 2 − shown to increase Na reabsorption. The mitochondrial respiratory chain is a major source of ROS in mTAL but it is unknown if changes in Na delivery to this nephron segment result in changes in mitochondria ROS production. We recently reported the use of a novel mitochondrial‐targeted H 2 O 2 ‐specific fluorescence indicator (Mito‐PY1) and demonstrated that increased luminal flow and Na delivery to the mTAL significantly increased mitochondrial [H 2 O 2 ]. In the present study, mTAL were isolated from Sprague Dawley rats and microperfused with Hanks' balance salt solution ([Na 143mM]) at 5nl/min. As flow rate was increased to 20nl/min for 30min Mito‐PY1 intensity increased 33±9 fluorescence units (FU) compared to 7±5 for the time control (n=6; P<0.05). Pretreatment of mTAL with Na transporter inhibitors furosemide (100μM; n=4) or ouabain (4mM; n=4) significantly attenuated H 2 O 2 response to flow (13±5 and 10±5 FU respectively vs. non‐treated mTAL 29±7 FU). Increases of [Na] from 60 to 143 mM at a fixed flow rate of 5nl/min increased (P<0.05) mitochondrial H 2 O 2 . Together, the data indicate that increased Na transport is a necessary part of the signaling pathway for increased mTAL mitochondria H 2 O 2 production in response to Na delivery. (HL‐29587)