The Effects Of Irbesartan on Sympathetic Activity in Humans

In experimental settings, angiotensin II has been reported to interact with the sympathetic nervous system both centrally and peripherally. Direct evidence for this mechanism is limited in humans. We have examined the effect of AT1 receptor blockade on plasma noradrenaline during isometric handgrip exercise in healthy young volunteers. This study investigated the effects of five days pretreatment with 150mg/day irbesartan, a selective AT1-receptor antagonist on plasma noradrenaline during isometric handgrip exercise in nine healthy male volunteers (mean age 24.4 ± 0.2 (SD) years) in a double blind randomized crossover study. A match placebo was given to control group. The results showed that irbesartan did not affect resting haemodynamic and plasma noradrenaline levels. However, irbesartan pretreatment blunted the increase in plasma noradrenaline during exercise (placebo, from 225.3 ± 19.6 to 267.2 ± 16.4 pg/ml; irbesartan, from 212.9 ± 15.8 to 219.8 ± 15.1 pg/ml; irbesartan vs placebo, p<0.01). Irbesartan pretreatment also blunted the increase in mean arterial pressure during exercise (placebo, from 88.6 ± 2.8 to 100.9 ± 4.0 mmHg; irbesartan, from 85.4 ± 3.1 to 88.9 ± 3.4 mmHg; irbesartan vs placebo, p<0.01). These data indicated a beneficial effect of AT1-blocker on sympathetic activity during the stimulus of isometric handgrip exercise in humans.