The effects of an arginine-free enteral diet on wound healing and immune function in the postsurgical rat.

Critically ill patients have increased rates of sepsis partly due to a down-regulated immune system. Nutrients may modulate the immune system. The following studies were performed to determine whether arginine is one of these "essential" nutrients for the immune system. Thirty-two male Sprague-Dawley rats (weighing 175 g) were divided into two groups that were pair-fed with either an elemental, arginine-supplemented enteral diet, or the same diet with arginine removed and replaced with glycine. Both diets were isocaloric, isoosmolar, and isonitrogenous. After 6 days on the diet, animals underwent testing. There were no significant differences between the arginine-supplemented and the arginine-free diet groups in blood glucose or hematocrit. The arginine-supplemented animals had higher serum albumin (4.1 +/- 0.1 mg/dL v 3.6 +/- 0.1 mg/dL; P = .035) and serum protein levels (5.2 +/- 0.1 mg/dL v 4.3 +/- 0.1 mg/dL; P = .041); and had higher thymus gland (0.53 +/- 0.03 g v 0.44 +/- 0.02 g; P less than .0001) and spleen weights (0.66 +/- 0.01 g v 0.57 +/- 0.01 g; P less than .01). Daily total urinary nitrogen excretion, nitrogen balance, and weight gain showed a tendency for the arginine-supplemented animals to retain more of their nitrogen calories. There was no difference in the amount of hydroxyproline (OHP) found in the wound cylinders of either group (both 25.6 micrograms OHP/cm polytetrafluoroethylene) but the arginine-supplemented group's wounds had greater wound bursting strengths (429 +/- 3 g/cm v 350 +/- 7 g/cm; P = .044).(ABSTRACT TRUNCATED AT 250 WORDS)