Key result
Dietary sodium deprivation increased renal ANG I (296 vs 161 fmol/g) and ANG II (216 vs 98 fmol/g), while ACE inhibition increased renal ANG I 2.8-fold and decreased ANG II by 75-78%.
Why the study?
Do dietary sodium changes and ACE inhibition alter renal tissue angiotensin I and II levels and ACE activity in rats?
Do dietary sodium changes and ACE inhibition alter renal tissue angiotensin I and II levels and ACE activity in rats?
p-value: p=< 0.01
Dietary sodium deprivation upregulates renal ACE activity and angiotensin levels, while ACE inhibition markedly reduces renal angiotensin II in rats.
Rat data on sodium/ACE effects on renal angiotensin should not yet change practice; leaves open human translation and mechanistic studies.
This study was designed to improve and validate methods for the accurate and consistent quantitation of angiotensin (ANG) I and II levels in rat kidney and to determine the effects on renal ANG I and II of changes in dietary sodium intake and ANG-converting enzyme (ACE) inhibition. Kidneys from pentobarbital-anesthetized rats were rapidly removed and homogenized in methanol before extraction and purification of ANG peptides by solid-phase extraction and high-performance liquid chromatography (HPLC). Recoveries of 125I-ANG I and II were greater than 80%. Reversed-phase HPLC of the partially purified methanol extract showed that greater than 75% of the ANG I- and greater than 82% of the ANG II-like immunoreactivity coeluted with ANG I and II, respectively. Dietary sodium deprivation (0.003 meq/g) and excess (1.34 meq/g) for 7 days significantly (P less than 0.01) increased and decreased renal ANG I (296 +/- 30 and 82.6 +/- 15.8 vs. 161 +/- 18 fmol/g) and ANG II (216 +/- 16 and 45.6 +/- 11.8 vs. 98 +/- 16 fmol/g) contents, respectively. Plasma ANG I and II levels showed similar changes. ACE activity was significantly upregulated by sodium deprivation in both kidney (44% increase) and plasma (30% increase). In rats fed normal chow, infusion of enalaprilat for 1 h abolished plasma ACE activity but decreased renal ACE activity by only 58%. ACE inhibition increased renal and plasma ANG I levels 2.8- and 12-fold, respectively, and decreased renal and plasma ANG II levels 75-78%.(ABSTRACT TRUNCATED AT 250 WORDS)
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Fox et al. (1992) studied this question. Dietary sodium modification and enalaprilat vs. Normal chow was evaluated on Renal angiotensin I and II levels (p=< 0.01). Dietary sodium deprivation increased renal ANG I (296 vs 161 fmol/g) and ANG II (216 vs 98 fmol/g), while ACE inhibition increased renal ANG I 2.8-fold and decreased ANG II by 75-78%.
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