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Angiotensin II‐induced hypertension stimulates thick ascending limb NaCl absorption by increasing O 2 −
Author(s) -
Silva Guillermo B,
Garvin Jeffrey L
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.969.28
Subject(s) - medicine , endocrinology , angiotensin ii , chemistry , protein kinase c , furosemide , renin–angiotensin system , kidney , receptor , blood pressure , kinase , biochemistry
Renal medullary O 2 − increases in angiotensin‐induced hypertensive (Ang‐IH) rats. We have shown that O 2 − increases thick ascending limb (TAL) Na transport, but the effect of Ang‐IH on the TAL is unknown. We hypothesized that TAL Na absorption in Ang‐IH rats is enhanced due to elevated O 2 − levels and protein kinase C (PKC) α activity. We measured O 2 − levels, furosemide‐sensitive oxygen consumption (FSQO 2 ) as a measure of Na transport and PKCα activity in TAL suspensions from control and Ang‐IH rats. In TALs from Ang‐IH rats O 2 − levels were 2.5±0.5 compared to 0.8±0.3 arbitrary units (AU)/min/mg protein for controls ( p <0.05). FSQO 2 also increased (25±3 to 36±2 % of total QO 2; p <0.05). Tempol, a O 2 − scavenger, infused into 1 kidney of Ang‐IH rats decreased O 2 − levels from 2.3±0.4 to 1.3±0.2 AU/min/mg protein ( p <0.05) and FSQO 2 from 33±2 to 24±2 % of total QO 2 ( p <0.05). Tempol had no effect on O 2 − or FSQO 2 in controls. Tempol did not alter blood pressure of Ang‐IH rats. In Ang‐IH rats PKCα activity was 3.7±0.9 compared to 1.1±0.2 AU/mg protein ( p <0.05) in controls. Tempol infusion into 1 kidney of Ang‐IH rats reduced PKCα activity from 3.0±0.6 to 0.6±0.1 AU/mg protein ( p <0.05). Infusion of the PKCα inhibitor Gö6976 into one kidney of Ang‐IH rats reduced FSQO 2 from 38±3 to 26±3 % of total QO 2 ( p <0.05). We conclude that in Ang‐IH rats TAL NaCl absorption is enhanced due to elevated O 2 − and PKCα activity rather than increased blood pressure.