[The sympathetic and renin-angiotensin systems are complementary in blood pressure regulation]

The consequences of a chronic destruction of sympathetic nerves or of the blockade of the renin angiotensin system (RAS) on the blood pressure (BP) level and its spontaneous variability were studied using a computerized method which allows a continuous monitoring of BP in conscious unrestrained rats. Guanethidine, used to lesion the sympathetic fibres did not alter the BP level but significantly enhanced its variability. On the opposite, angiotensin converting enzyme inhibition decreased the BP level without changing its variability. It is concluded that both systems play a complementary role as the RAS determines the long-term BP level while the sympathetic nerves control its short-term variability in conscious animals.