Acute protein-calorie malnutrition impairs wound healing: a possible role of decreased wound nitric oxide synthesis.

BACKGROUND: Nitric oxide is synthesized in wounds. Systemic inhibition of wound nitric oxide synthesis decreases wound collagen accumulation and wound mechanical strength. The role of nitric oxide during impaired healing is not known. In a model of impaired wound healing induced by acute protein-calorie malnutrition, we correlated wound healing parameters with wound nitric oxide synthesis. STUDY
DESIGN: One group of Sprague-Dawley rats was rendered acutely malnourished by restricting its food intake to 50 percent of the food intake of an ad libitum-fed control group. Wound collagen accumulation and types I and III collagen gene expression were measured 10 days postwounding in subcutaneously implanted polyvinyl alcohol sponges. Nitric oxide synthesis was determined in wound fluid and in supernatants of wound cell cultures.
RESULTS: Animals with acute protein-calorie malnutrition lost 10.4 +/- 0.8 percent, while controls gained 17.5 +/- 1.2 percent of their original body weight. Protein-calorie malnutrition reduced sponge hydroxyproline contents (995 +/- 84 compared with 1,580 +/- 109 micrograms/100 mg sponge, p < .001), indicating diminished wound collagen accumulation. Gene expression of type III, but not type I, collagen was decreased in wounds of protein-calorie malnutrition animals. Nitrite/nitrate and citrulline concentrations in wound fluid (p < .01) and in wound cell supernatants (p < .001) were also lower in protein-calorie malnutrition animals, indicating a net decrease in nitric oxide production.
CONCLUSIONS: Impaired wound collagen accumulation caused by protein-calorie malnutrition may be a reflection of reduced nitric oxide synthesis within the wound.