The renin angiotensin system in childhood hypertension: selective increase of angiotensin-(1-7) in essential hypertension.

OBJECTIVE

We examined the activity of the renin-angiotensin system (RAS) in normotensive and hypertensive children.

STUDY

DESIGN

Hypertensive patients (12 with renovascular hypertension and 15 with essential hypertension) and 32 normotensive subjects were evaluated at a Pediatric Nephrology Center. Blood samples for plasma renin activity (PRA) and angiotensin peptides measurements were obtained once from normotensive subjects and before and after treatment from hypertensive patients. Plasma samples were extracted using Bond-Elut cartridges (Analytichem International, Harbor City, Calif), and peptide concentrations were determined by radioimmunoassay (RIA).

RESULTS

PRA, Angiotensin I (Ang I), Angiotensin II (Ang II), and Angiotensin-(1-7) [Ang-(1-7)] levels were significantly higher in renovascular hypertensive patients than in normotensive children (3.3 +/- 1.2 vs 0.40 +/- 0.22 ng Ang I/mL/hour, 81.4 +/- 24.8 vs 26.4 +/- 13.4 pg/mL, 59.3 +/- 17.0 vs 21.4 +/- 8.7 pg/mL, 41.0 +/- 10.5 vs 16.2 +/- 7.9 pg/mL, respectively). The surgical treatment normalized blood pressure, PRA, and angiotensins levels. In contrast with renovascular disease, only Ang-(1-7) levels were significantly increased in essential hypertensive patients compared with normotensive (78.8 +/- 22.8 vs 16.2 +/- 7.9 pg/mL). Treatment with calcium channel blockers did not alter the RAS measurements.

CONCLUSION

Our data show different RAS profiles in childhood hypertension and suggest a blood pressure-independent change of Ang-(1-7) in essential hypertension.