Abstract
Background: Dietary supplementation with a fish oil and arginine-enriched immunoenhancing diet (Impact; Sandoz Nutrition, Minneapolis, MN) in a rat cardiac allograft model using donor-specific transfusion (DST) and cyclosporin (CsA) resulted in significant prolongation of cardiac allograft survival with many animals developing long-term tolerance. This study was done to determine whether arginine or fish oil was the active ingredient. Methods: A standard AIN-76A diet was modified to include either 10% fish oil, 2% arginine, or 5% arginine with or without fish oil. Diets were fed to Lewis strain rats that received Ax C9935 Irish (ACI) heterotopic cardiac allografts beginning on day 1 and continuing indefinitely. A DST (1.0 mL ACI whole blood) was given with 10 mg/kg CsA on day 1 relative to transplant and 2.5 mg/kg/ d on days 0 to 6. Groups of animals receiving AIN-76A diet fortified with 2% glycine and animals receiving a DST or DST/CsA and regular laboratory chow served as controls. Results: Mean survival times ± SEM in days were as follows: untreated, 7.1 ± 0.4; CsA/ 2% glycine, 8.5 ± 0.6; DST only, 9.6 ± 1.1; DST/CsA, 26.6 ± 6.4; CsA/2% arginine, 25.5 ± 3.9; DST/CsA/2% arginine, 68.7 ± 8.9; DST/CsA/5% arginine, 90.1 ± 31.1; CsA/fish oil, 73.6 ± 26.1; and DST/CsA/fish oil/5% arginine, 90.1 ± 31.1. The effect of arginine was slightly dose dependent and was seen best in combination with DST, but the effect of fish oil was not enhanced by DST. Conclusions: Both fish oil and arginine dietary supplementation significantly improved allograft survival but through different mechanisms (DST vs non-DST dependent). (Journal of Parenteral and Enteral Nutrition
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