High Blood Pressure
L-arginine infusion reduces blood pressure in preeclamptic women through
nitric oxide release.
Facchinetti F; Longo M; Piccinini F; Neri I; Volpe A
J Soc Gynecol Investig 1999 Jul-Aug;6(4):202-7
OBJECTIVE: This study investigates the biochemical and cardiovascular
effects of L-arginine administration in normotensive pregnant women and
women with preeclampsia. METHODS: The study groups consisted of 12 women
with uncomplicated pregnancies and 17 preeclamptic patients, four of whom
were on antihypertensive treatment. In both groups, saline infusion was
started, followed by 30 g L-arginine administration, and finally more
saline. Blood pressure was recorded every 5 minutes and blood samples
were collected for measurement of serum citrulline, arginine, and nitrite
levels. Amino acid assays were done by using high-performance liquid chromatography
with fluorometric detection. RESULTS: L-Arginine infusion was associated
with a significant reduction of blood pressure in both groups, the decrease
being greater in the women with preeclampsia. Baseline serum citrulline
and arginine levels were not significantly different between the two groups.
L-Citrulline levels were significantly increased during infusion of L-arginine,
and the increase was significantly lower in the women with preeclampsia.
Serum nitrite levels were increased only in controls and not in preeclampsia
patients. The total citrulline production stimulated by L-arginine was
related inversely to baseline blood pressure values and was unrelated
to clinical parameters such as gestational age at delivery, birth weight,
and Apgar score. CONCLUSIONS: L-Arginine load in pregnant women is associated
with increased nitric oxide (NO) production and hypotension. Despite a
reduced ability to produce NO, patients with preeclampsia may benefit
from L-arginine supplementation. Overall, these findings partially support
the hypothesis that preeclampsia is characterized by a dysfunction of
the L-arginine-NO pathway.