ARGININE - ESSENTIAL AMINO-ACID FOR INJURED RATS

Abstract

The influence of arginine supplements on growth and healing of skin incisional wounds was studied in rats fed either a chemically defined diet lacking arginine or a laboratory chow containing 1.8% arginine. Rats fed the arginine-free diet grew more poorly than did arginine-supplemented rats (1.8 vs 7.0 g/day) in the preoperative period. After operation arginine-deficient animals grew very poorly (1 g/day); arginine-supplemented rats gained 4.3 g/day. Arginine-deficient animals showed impaired wound healing, as judged by the breaking strengths of their incisions 10 days after wounding (228 vs. 293 g for the arginine-supplemented rats). Arginine-deficient rats also showed decreased collagen deposition in a specific wound site, as indicated by the decreased content in hydroxyproline in sponge granulomas (2.5 vs. 4.2 mg/100 mg of sponge for the arginine-supplemented rats). In rats fed commerical chow, 1% arginine decreased the postoperative weight loss associated with injury (0.7 vs. 5.2 g) in 1 experiment and improved wound strength in 2 experiments (312 vs. 188 g in 1 experiment and 309 vs. 246 g in another). Arginine also increased hydroxyproline deposition in a specific wound area (5.5 vs. 4.1 mg in 1 experiment and 3.1 vs. 1.9 mg in another). Apparently arginine has 2 roles in wounded animals. It is essential for the synthesis of the increased amounts of reparative collagen required for wound healing, and it decreases some of the negative aspects of the metabolic responses to injury. These may be associated with an arginine-induced growth hormone release.