Effect of l-glutamine on pulmonary hypertension in the perfused rabbit lung.
The effects of l-glutamine on pulmonary hypertension in the isolated perfused rabbit lung were investigated. Pulmonary hypertension was produced by the thromboxane-A2 mimetic U46619. l-Glutamine at a dose of 0.04 mM produced a sustained increase in pulmonary artery pressure (PAP) and subsequent administration of an equimolar dose of l-arginine did not affect PAP. l-Glutamine at a dose of 0.5 mM transiently increased PAP, which then decreased to baseline (pre-glutamine) values. When endogenous nitric oxide (NO) synthesis was inhibited with NG-nitro-l-arginine methylester, l-glutamine at a dose of 0.04 mM decreased PAP. These results demonstrate that the effect of l-glutamine on PAP during pulmonary hypertension depends upon dose, time and the presence of endogenous NO synthesis. We believe that the results can be explained by two different effects of l-glutamine, namely a direct inhibition of NO release by glutamine and the donation of nitrogen atoms by glutamine for additional NO or other vasodilator synthesis. Since plasma glutamine levels are 0.4-0.7 mM, endogenous l-glutamine may play a modulatory role during pulmonary hypertension.
Xu
H
H
Department of Anesthesia, Stanford University Medical Center, CA 94305-5123.
Pearl
R G
RG
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D005973:Glutamine / Q000494:pharmacology*; D006976:Hypertension, Pulmonary / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D010477:Perfusion; D011651:Pulmonary Artery / Q000187:drug effects / Q000503:physiopathology; D011817:Rabbits
D005973:Glutamine; D009569:Nitric Oxide; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester