Two cases suggesting a role for the L-arginine nitric oxide pathway in neonatal blood pressure regulation.

Endogenous nitric oxide produced from L-arginine is a potent vasodilator that may be involved in blood pressure regulation. A male infant with argininosuccinate lyase deficiency, who could not synthesize L-arginine, was hypertensive prior to L-arginine replacement. The infusion of L-arginine resulted in a decrease in blood pressure. A three-fold increase in the dose of L-arginine further decreased blood pressure. On discontinuing the infusion of L-arginine, the patient's blood pressure increased. A female infant undergoing an L-arginine challenge test had a decrease in blood pressure during L-arginine infusion which resolved when the L-arginine infusion was discontinued. These two cases suggest that nitric oxide production from L-arginine may play a role in the normal regulation of systemic blood pressure.