Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/25/2007
Publication Date: 10/10/2007
Citation: Jahoor, F., Badaloo, A., Villalpando, S., Reid, M., Forrester, T. 2007. Arginine flux and intravascular nitric oxide synthesis in severe childhood undernutrition. American Journal of Clinical Nutrition. 86(4):1024-1031. Interpretive Summary: In earlier studies we found that malnourished children who also had edema had low blood levels of an amino acid called arginine when compared to malnourished children who did not have edema. A compound made from arginine is nitric oxide which has numerous important roles, the most important being regulation of blood pressure. Arginine itself has been shown to be very important for a healthy immune system. In this study we wanted to find out whether children with edematous malnutrition were producing enough arginine compared to malnourished children without edema, and the extent to which they were converting arginine to nitric oxide. We found that the children with edema made arginine slower and had lower blood levels compared to the children without edema. However, they were still able to convert arginine to nitric oxide at the same rate as the children without edema. The decreased availability of arginine in malnourished children with edema may be one reason why their immune systems do not work as well as the immune systems of malnourished children without edema.
Technical Abstract: Although nutritionally dispensable amino acids are not essential in the diet, adequate synthesis is necessary for maintenance of good health. Whereas children with edematous severe childhood undernutrition (SCU) can maintain production rates of glycine and serine despite a slower body protein breakdown rate, it is unknown whether the same is true for the semidispensable amino acid arginine. We aimed to measure arginine flux and intravascular nitric oxide synthesis in children with SCU. Arginine flux and the fractional and absolute synthesis rates of plasma nitrite plus nitrate were measured postabsorptively by using a 6-h infusion of [(15)N(2)]-arginine in 2 groups of children with edematous (n = 14) or nonedematous (n = 7) SCU when they were infected and malnourished (postadmission day approximately 3; clinical phase 1), when they were no longer infected (postadmission day approximately 15; clinical phase 2), and when they were recovered (postadmission day approximately 55; clinical phase 3). Arginine flux was slower (P < 0.01) and plasma arginine concentrations were lower in the edematous group than in the nonedematous group at clinical phase 1. At clinical phase 2, flux doubled to a value that was not significantly different from the value at clinical phase 3. There were no significant differences in the plasma concentration or fractional or absolute synthesis rate of plasma nitrite plus nitrate between the groups at any clinical phase and among clinical phases within each group. Whereas children with nonedematous SCU can maintain arginine flux at the same rate as when recovered, children with edematous SCU cannot. The slower arginine flux was not, however, associated with slower nitric oxide synthesis.