Colonic acetate in the circulating acetate pool of the infant pig

To identify potential sites of acetate utilization and synthesis, we studied the contribution of colonic acetate to the circulating acetate pool in six neonatal pigs by the simultaneous i.v. infusion of [3H]acetate and colonic infusion of [14C]acetate. In the fasting state, the mean (+/- SEM) acetate concentration was 17 +/- 1 mumol/L in peripheral venous blood, 28 +/- 4 mumol/L in the femoral artery, and 46 +/- 4 mumol/L in portal blood. This concentration gradient implies that acetate was utilized either by peripheral tissues alone or by both liver and peripheral tissues. At the end of the 2-h intracecal acetate infusion, mean acetate concentration increased in the femoral artery to 186 +/- 20 mumol/L and in the portal vein to 333 +/- 31 mumol/L. In the fasted state, mean acetate concentration in the portal vein was on average 63% higher than the acetate concentration of the femoral artery, whereas specific radioactivity of the [3H]acetate in the portal vein was only 5% of that in the femoral artery. It is possible, therefore, that a high proportion of the arterial input of acetate is utilized by the portal-drained viscera. Our study identified the gastrointestinal tract as an important site of acetate utilization in the fasted state. Further, it showed that colonic acetate was efficiently absorbed and utilized in the gastrointestinal tract of infant pigs.