Splanchnic buffering of metabolic acid during early endotoxemia

Purpose: We sought to determine the sites of metabolic acid production and clearance during acute endotoxemia. Materials and Methods: In 10 pentobarbital-anesthetized dogs, flow was measured (ultrasonic probes) for the portal vein, hepatic artery, and renal artery. Catheters were inserted into the hepatic vein, pulmonary artery, renal vein, and portal vein. Measurements of blood gases and strong ions were obtained from each site during control conditions and after 30 minutes of intravenous infusion of 1 mg/kg of Escherichia coli endotoxin. The total metabolic acid flux across each organ was calculated using the standard base excess formula and the effective strong ion difference method. Paco₂ was maintained by controlled ventilation. Results: Mean arterial pH decreased from 7.34 to 7.22 with acute endotoxemia. Although transvisceral pH gradients revealed net acid release, the source of this was purely respiratory (carbon dioxide). During early endotoxemia, the gut significantly increased metabolic acid uptake l36.60 ± 6.60 mmol/h, P < .05). Conclusions: We conclude that during early endotoxemia in the dog, the gut is a major site of metabolic acid removal.