Characterization of angiotensin-(1-7) in the urine of normal and essential hypertensive subjects.
A total of 31 healthy volunteers [39 +/- 7 (SD) years] and 18 untreated essential hypertensive subjects [43 +/- 9 years] collected urine for 24 h after a physical examination and laboratory tests. Radioimmunoassay measurements of angiotensin-(1-7) [Ang-(1-7)] in urine and plasma were done as described previously. Sitting systolic and diastolic blood pressures (+/- SD) averaged 118 +/- 11/74 +/- 7 mm Hg and 146 +/- 16/96 +/- 8 mm Hg in normal and essential hypertensive subjects, respectively (P < .001), whereas 24 h urinary volume was not different in normal and essential hypertensive subjects (P > .05). The concentration of Ang-(1-7) in the urine of normal subjects averaged 62.6 +/- 22.6 pmol/L corresponding to a urinary excretion rate of 98.9 +/- 44.7 pmol/24 h. Concurrent measurements of plasma Ang-(1-7) showed that the content of Ang-(1-7) in urine was 2.5-fold higher than that measured in the plasma. In contrast, untreated essential hypertensive subjects had lower concentrations and 24 h urinary excretion rates of Ang-(1-7) averaging 39.4 +/- 18.0 pmol/L and 60.2 +/- 14.6 pmol/24 h, respectively, (P < .001). Differences in the excretory rate of Ang-(1-7) between normal volunteers and essential hypertensive subjects were not modified by normalization of the data by urinary creatinine excretion rates. Urinary concentrations of Ang-(1-7) correlated inversely with systolic, diastolic and mean arterial pressures (r = -0.48, P < .001). Both urinary Ang-(1-7) [odds ratio of 0.92 (95% CI: 0.88-0.97)] and age were independent predictors of systolic blood pressure. These studies demonstrated the presence of Ang-(1-7) in urine and the existence of reduced levels of the heptapeptide in individuals with untreated essential hypertension. The relatively higher concentrations of Ang-(1-7) in urine compared to plasma agrees with data that showed that Ang-(1-7) may contribute to the regulation of blood pressure. The inverse association between Ang-(1-7) and arterial pressure provides a potential marker for the characterization of forms of essential hypertension associated with reduced production or activity of vasodilator hormones.
Ferrario
C M
CM
The Hypertension Center, The Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina 27157, USA. cferrari@bgsm.edu
Martell
N
N
Yunis
C
C
Flack
J M
JM
Chappell
M C
MC
Brosnihan
K B
KB
Dean
R H
RH
Fernandez
A
A
Novikov
S V
SV
Pinillas
C
C
Luque
M
M
D000328:Adult; D000367:Age Factors; D000803:Angiotensin I; D000804:Angiotensin II / Q000097:blood / Q000652:urine*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000652:urine*; D007668:Kidney / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood / Q000652:urine*
D010446:Peptide Fragments; D000804:Angiotensin II; D000803:Angiotensin I; C118790:angiotensin I (1-7)