Impact of enteral and parenteral nutrition on hepatic and muscle glucose metabolism

ABSTRACT. Liver and muscle metabolism were assessed in dogs adapted to long-term total parenteral (TPN) and enteral (TEN) nutrition. Studies were done in 13 conscious long-term catheterized dogs in which sampling (artery, portal and hepatic vein, and iliac vein), infusion catheters (inferior vena cava, duo-denum), and transonic flow probes (hepatic artery, portal vein, and iliac artery) were implanted. Fourteen days after surgery dogs were grouped to receive TPN or TEN. After 5 days of TPN/TEN, substrate balances across the liver and limb were assessed. The liver was a marked net consumer of glucose in both groups (23.6 ± 3.3 vs 22.6 ± 2.8 μmol · kg-1 · min-1, TPN vs TEN) despite near normoglycemia (6.5 ± 0.3 vs 6.7 ± 0.2 mmol/L). Arterial insulin levels were higher during TEN (96 ± 6 vs 144 ± 30 pmol/L; p <.05). The majority (79 ± 13 vs 76%±7%) of the glucose taken up by the liver was released as lactate