Increased sympathetic activity in normotensive offspring of malignant hypertensive parents compared to offspring of normotensive parents

Malignant hypertension seems to be the consequence of very high blood pressure. Furthermore, an increase in sympathetic andrenin-angiotensin system activity is considered to be the main mechanisms producing malignant hypertension. In the presentstudy, 10 offspring of malignant hypertensive (OMH) parents (age 28 ± 5 years, 7 males, 3 females, 2 white and 8 non-white) and10 offspring of normotensive (ONT) parents (age 28 ± 6 years, 2 males, 8 females, 3 white and 7 non-white) were evaluated. TheOMH group had significantly higher (P < 0.05) casual blood pressure (125 ± 10/81 ± 5 mmHg) compared with ONT (99 ± 13/67± 5 mmHg). The increase in blood pressure was greater in OMH (∆ SBP = 17 ± 2 vs ∆ SBP = 9 ± 1 mmHg in ONT) during coldpressor testing, but they had a lower increase in heart rate ( ∆ HR = 13 ± 2 vs ∆ HR = 20 ± 3 bpm in ONT) during isometric exercise(handgrip test). Sympathetic activity, measured by microneurography, was significantly higher (P < 0.05) before exercise inOMH (17 ± 6 vs 11 ± 4 burst/min in ONT) and exhibited a greater increase (∆ = 18 ± 10 vs ∆ = 8 ± 3 burst/min in ONT) duringisometric exercise. This study showed increased sympathetic activity in OMH before exercise and a greater response duringisometric exercise, suggesting an autonomic abnormality before exercise and a greater sympathetic response to physical stressin OMH compared to ONT.Key words: Malignant hypertension; Offspring of malignant hypertensive parents; Sympathetic activity; MicroneurographyPublication supported by FAPESP.Received September 17, 2007. Accepted August 19, 2008