Splanchnic metabolism in exercising man

Using a single injection of indocyanine green dye, estimated hepatic plasma and blood flow were determined in six normal young males during the 30th to 60th min of exercise requiring 10–12 kcal/min (2.04– 2.49 liters O2 per min). Subjects were fasted 15–18 hours. During hepatic flow measurements four determinations of splanchnic A-V differences of triglyceride (TG), free fatty acid (FFA), phospholipid (PL), ketone bodies, and glucose were made from radial arterial and hepatic venous sampling sites. Splanchnic A-V concentration differences for TG and PL varied randomly with time from positive to negative values indicating no net production whereas FFA was uniformly taken up by splanchnic organs at an average rate of 64 μm/min. Average splanchnic ketone body production was 20 mg/min and glucose production averaged 295 mg/min. Complete oxidation by skeletal muscle of lipid substrate released by splanchnic organs could account for less than 5% of total caloric expenditure; glucose production accounted for an average of 10.4%. One to two determinations of splanchnic A-V lactate, CO2, and O2 concentrations in four men indicated continued uptake of lactate (average 50 mg/min) during exercise with RQ values approaching zero. lipid metabolism; exercise, hepatic blood flow, and metabolism; energy metabolism Submitted on January 15, 1965