Characterization of angiotensin-(1-7) in the urine of normal and essential hypertensive subjects

Am J Hypertens. 1998 Feb;11(2):137-46. doi: 10.1016/s0895-7061(97)00400-7.

Abstract

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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Age Factors
  • Angiotensin I
  • Angiotensin II / blood
  • Angiotensin II / urine*
  • Cross-Sectional Studies
  • Female
  • Humans
  • Hypertension / blood
  • Hypertension / urine*
  • Kidney / physiopathology
  • Male
  • Middle Aged
  • Peptide Fragments / blood
  • Peptide Fragments / urine*

Substances

  • Peptide Fragments
  • Angiotensin II
  • Angiotensin I
  • angiotensin I (1-7)