Dietary Na and ACE inhibition effects on renal tissue angiotensin I and II and ACE activity in rats.
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)
Fox
J
J
Department of Physiology, Tulane University School of Medicine, New Orleans, Louisiana 70112.
Guan
S
S
Hymel
A A
AA
Navar
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LG
D000803:Angiotensin I / Q000378:metabolism*; D000804:Angiotensin II / Q000378:metabolism*; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004032:Diet; D007668:Kidney / Q000378:metabolism*; D008297:Male; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012084:Renin-Angiotensin System / Q000187:drug effects; D012964:Sodium / Q000008:administration & dosage* / Q000494:pharmacology
D000806:Angiotensin-Converting Enzyme Inhibitors; D000804:Angiotensin II; D000803:Angiotensin I; D012964:Sodium; D007703:Peptidyl-Dipeptidase A