Effect of route of nutrition on recovery of hepatic organic anion clearance after fasting.
Previous work documented a 40% depression of hepatic indocyanine green (ICG) clearance (ClICG) in pigs fasted to 20% weight loss, with return to normal within 12 days of food refeeding. ClICG in pigs is insensitive to changes in hepatic blood flow but very sensitive to changes in hepatic function (HF). Serial ClICG determinations were performed to quantify the effect of route of nutrient delivery on recovery of HF. Fourteen pigs were fasted to 20% weight loss (12.8 days average) with both gastrostomy and intravenous catheters placed in each animal midway through the fast. ClICG was measured before fast, after fast, and after 12 days refeeding through the enteral or parenteral route at 125 kcal/kg/day with isonitrogenous, isocaloric diets containing 9% fat. Urine and stool were analyzed for total nitrogen. No significant differences appeared between groups in nitrogen output during fasting (4.5 +/- 1.2 gm/kg enteral, 4.6 +/- 1.2 gm/kg parenteral), in nitrogen intake (800 +/- 19 mg/kg/day enteral, 810 +/- 10 mg/kg/day parenteral), or in before or after fast ClICG, but enteral feeding produced more positive nitrogen balance. ClICG improved significantly with enteral but not with parenteral feeding. Enteral feeding produces faster nitrogen accrual and reverses the depression of major pathways of bilirubin and organic anion excretion associated with malnutrition. Parenteral feeding failed to improve organic anion clearance despite weight gain.