The role of nitric oxide in the central control of blood pressure.

In these studies blood pressure responses to intracerebroventricular (i.c.v.) infusions were recorded in anesthetized rats. NO donors caused a fall in blood pressure, whereas L-NAME, which blocks the enzyme (NOS) that produces NO, caused a rise in blood pressure. Calcium, i.c.v., stimulates NOS to lower blood pressure. The depressor action of NO is reduced by blocking the action of cGMP. This central NO/cGMP system is tonically active to maintain blood pressure at a normal level.