Renal tissue angiotensin II: response to infusions of angiotensin I and an angiotensin-converting enzyme inhibitor.
A procedure for the collection, processing, extraction, separation, and measurement of renal tissue angiotensin II [ANG-(1-8)] is described. The arterial plasma and renal tissue concentrations of ANG-(1-8) were examined in anesthetized Sprague-Dawley male rats (10 to 12 weeks of age) given an intravenous saline infusion (group 1; n = 6), an intravenous bolus infusion of 0.5 microgram angiotensin I (group 2; n = 6), or an intravenous bolus of an angiotensin-converting enzyme inhibitor (group 3; n = 6). Plasma and renal tissue were collected at the peak mean arterial pressure (MAP) response. The mean (+/- SEM) concentration of ANG-(1-8) in the group given the saline vehicle was 12 +/- 2 fmol/mL in the plasma and 2.4 +/- 0.3 pmol/g in the renal tissue. The angiotensin I bolus significantly increased MAP by 40%. Following the angiotensin I infusion, at the time of peak MAP response, the concentration of the circulating and renal tissue ANG-(1-8) were 12-fold and twofold higher, respectively, compared with the saline vehicle. The angiotensin-converting enzyme inhibitor significantly decreased MAP by 10% and decreased the circulating and renal tissue ANG-(1-8) levels by 75% and 62.5%, respectively, compared with the saline vehicle. The rapid conversion of exogenous angiotensin I to ANG-(1-8) in renal tissue provides direct evidence that renal tissue can generate de novo ANG-(1-8) from a circulating precursor. Furthermore, plasma and renal tissue respond similarly to acute angiotensin-converting enzyme inhibition.
Reams
G
G
Department of Medicine, University of Missouri, Columbia 65212.
Villarreal
D
D
Wu
Z
Z
Bauer
J H
JH
D000803:Angiotensin I / Q000008:administration & dosage / Q000494:pharmacology*; D000804:Angiotensin II / Q000032:analysis* / Q000097:blood; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D007263:Infusions, Parenteral; D007668:Kidney / Q000737:chemistry*; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results
D000806:Angiotensin-Converting Enzyme Inhibitors; D000804:Angiotensin II; D000803:Angiotensin I