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Blood Oxygen Level Dependent Magnetic Resonance Imaging and Renal Tissue Oxygenation with Successive Inhibition of Renal Sodium Transport
Author(s) -
Warner Lizette,
Haas John A.,
Bolterman Rodney,
Gomez Sabas,
Joyner Michael J.,
Romero Juan Carlos
Publication year - 2008
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.22.1_supplement.761.5
Subject(s) - acetazolamide , furosemide , renal sodium reabsorption , reabsorption , renal cortex , chemistry , medulla , oxygenation , kidney , magnetic resonance imaging , cortex (anatomy) , medullary cavity , blood oxygen level dependent , medicine , endocrinology , biology , neuroscience , radiology
Functional renal oxygen consumption, V r O 2 is due to tubular reabsorption of sodium (T Na ) in the proximal and distal nephrons, resulting in compartments (cortex/medulla) with distinct V r O 2 /T Na relationships. Compartmental divisions promote non‐invasive imaging strategies like MRI, to indirectly assess tissue oxygenation, (P t O 2 ). However, the extent to which these regional P t O 2 differences are affected by successive T Na are not fully understood. The objective is to determine V r O 2 and intra‐renal regional alterations in P t O 2 directly and indirectly during successive T Na inhibition. It is hypothesized successive T Na inhibition is accompanied by intra‐renal regional changes in P t O 2 . Pigs (n=6) underwent MRI scans at baseline, furosemide and acetazolamide. Five days later, the right kidney was instrumented with P t O 2 sensors (cortex/medulla). P t O 2 was measured during drug infusions (identical to MRI exam). There was a decrease in V r O 2 , and a 40% and 30% increase in medullary and cortical P t O 2 following drug infusions. There was ~25% medullary and ~20–30% cortical decrease in BOLD signal with furosemide and acetazolamide administration, respectively. This study suggests successive inhibition of T Na is accompanied by intra‐renal regional P t O 2 changes and these changes are detectable with BOLD‐MRI, a non‐invasive imaging modality. Funding provided by NIH Grant (HL16496‐32), 2007 APS Porter Physiology Fellowship and the Mayo Foundation.