L-arginine pathway in the sepsis syndrome.
OBJECTIVE
To investigate the role of nitric oxide in the regulation of vascular tone in patients with the sepsis syndrome.


METHODS
Prospective, intervention study.


METHODS
Tertiary care hospital.


METHODS
Fifteen patients admitted to our medical intensive care unit with the diagnosis of sepsis syndrome by defined criteria.


METHODS
Eight patients received N omega-nitro-L-arginine (20 mg/kg, iv bolus) followed by L-arginine (200 mg/kg, iv bolus). Seven patients received L-arginine alone (200 mg/kg).


RESULTS
In the first group, hemodynamic and oxygen transport variables were recorded at baseline, during 45 mins after the injection of N omega-nitro-L-arginine, and during 45 mins after the administration of L-arginine. In the second group, hemodynamic parameters were recorded at baseline and during 15 mins after the administration of L-arginine. Data are mean +/- SEM. The administration of N omega-nitro-L-arginine was followed by hypertension (mean blood pressure increased from 89 +/- 8 to a maximum of 140 +/- 12 mm Hg) accompanied by a decrease in cardiac index (from 3.51 +/- 0.39 to a minimum of 2.65 +/- 0.21 L/min/m2) and an increase in right atrial and pulmonary artery occlusion pressure. Systemic vascular resistance index increased from 1871.1 +/- 302.3 to 3825.6 +/- 244.4 dyne.sec/cm5.m2, and pulmonary vascular resistance increased from 533.2 +/- 125.8 to 816.0 +/- 117.3 dyne.sec/cm5.m2. These changes induced by N omega-nitro-L-arginine were reversed by the administration of L-arginine. The administration of L-arginine to another group of patients caused transient hypotension (from 103 +/- 6 to 81 +/- 10 mm Hg) and an increase in cardiac index (from 3.57 +/- 0.15 to 4.74 +/- 0.54 L/min/m2). Both systemic and pulmonary vascular resistance indices decreased (from 1987.6 +/- 163.9 to 1251.4 +/- 231.5 dyne.sec/cm5.m2, and from 486.1 +/- 65.2 to 380.5 +/- 70.3 dyne.sec/cm5.m2). Parallel to the increase in oxygen transport due to the increase in cardiac output, oxygen consumption index increased significantly 1 min after L-arginine (from 127.0 +/- 19.0 to 182.5 +/- 37.3 mL/min/m2). All mentioned changes were statistically significant (p < .05).


CONCLUSIONS
A continuous basal release of nitric oxide plays a role in the regulation of systemic and pulmonary vascular tone in patients with sepsis syndrome. L-arginine has systemic and pulmonary vasodilatory actions.
Lorente
J A
JA
Unidades de Cuidados Intensivos, Hospital Ramón y Cajal, Madrid, Spain.
Landín
L
L
De Pablo
R
R
Renes
E
E
Liste
D
D
D000368:Aged; D000369:Aged, 80 and over; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005260:Female; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000502:physiology*; D019335:Nitroarginine; D010101:Oxygen Consumption / Q000187:drug effects; D011446:Prospective Studies; D011652:Pulmonary Circulation / Q000187:drug effects; D015657:Respiratory Transport / Q000187:drug effects; D018805:Sepsis / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology*
D019335:Nitroarginine; D009569:Nitric Oxide; D001120:Arginine