L-arginine improves endothelial and myocardial function after brain death.
BACKGROUND
Recently, we showed that brain death (BD) leads to a severe impairment of endothelial function.


METHODS
To test the hypothesis, that nitric oxide supply improves endothelial function, we infused L-arginine (40 mg/kg) in 6 dogs after BD induction (subdural balloon). Six vehicle-treated BD animals served as controls. Coronary blood flow (CBF), preload recruitable stroke work (PRSW), and plasma L-arginine and nitrite/nitrate levels were measured before and 6 hr after BD induction. In addition, endothelium-dependent vasodilatation after intracoronary application of acetylcholine (ACH) and endothelium-independent vasodilation after sodium nitroprusside (SNP) were assessed.


RESULTS
Six hours after BD, CBF decreased significantly in the control group (38.2+/-3.5 vs. 26.8+/-3.1 ml/min, P<0.05), whereas the decrease was less pronounced in the L-arginine group (41.8+/-6.9 vs. 36.0+/-1.2 ml/min, P<0.05 vs. control). Before BD, ACH led to a similar vasodilative response in both groups (81+/-6 vs. 75+/-7%). After BD, a paradox vasoconstriction occurred after ACH in the control group, while the vasodilative response did not change in the L-Arginine group (36+/-6 vs. 69+/-7%, P<0.05). The response to SNP did not differ between the groups and over the time. After BD PRSW decreased in both groups, however, it was still significantly higher in the L-arginine group (56+/-7 vs. 71+/-7 kerg, P<0.05). L-arginine (711+/-144 vs. 234+/-54 microM P<0.05) and nitrite/nitrate (39+/-3 vs. 27+/-3 microM P<0.05) levels were significantly higher in the L-arginine group.


CONCLUSIONS
L-arginine treatment prevents endothelial dysfunction and improves myocardial performance after BD via enhancement of endogenous nitric oxide synthesis.
Szabó
Gábor
G
Department of Cardiac Surgery, University of Heidelberg, Heidelberg, Germany. dzsi@hotmail.com
Soós
Pál
P
Heger
Ulrike
U
Mandera
Susanne
S
Buhmann
Volker
V
Bährle
Susanne
S
Kohl
Brigitte
B
Hagl
Siegfried
S
D000818:Animals; D001120:Arginine / Q000008:administration & dosage* / Q000097:blood; D001926:Brain Death / Q000503:physiopathology*; D003326:Coronary Circulation / Q000187:drug effects*; D004285:Dogs; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000503:physiopathology; D006321:Heart / Q000187:drug effects / Q000503:physiopathology; D006439:Hemodynamics / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects* / Q000502:physiology; D009206:Myocardium / Q000378:metabolism; D009566:Nitrates / Q000097:blood; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000097:blood; D009599:Nitroprusside / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
D009566:Nitrates; D009573:Nitrites; D014665:Vasodilator Agents; D009599:Nitroprusside; D009569:Nitric Oxide; D001120:Arginine