We sought to determine the role the liver might play in the regulation
of anion-cation balance during both stable baseline conditions and ac
ute endotoxemia. Ten pentobarbital sodium-anesthetized dogs were instr
umented at laparotomy with ultrasonic flow probes around the left rena
l artery, portal vein, and hepatic artery, and catheters were inserted
into the hepatic vein, portal vein, pulmonary artery, left renal vein
, and abdominal aorta. Measurements were obtained from each site at ba
seline and 30-45 min after the intravenous infusion of endotoxin. The
total anion flux across the liver was calculated from the strong-ion d
ifference. At baseline, the Liver removed anions from the circulation
(-0.34 meq/min). With early endotoxemia, however, the liver switched t
o the release of anions (0.12 meq/min; P = 0.0046). After endotoxin ad
ministration, the gut, which was neutral at baseline, began to take up
anions (-0.47 meq/min; P = 0.008). Anion flux across the lung and kid
ney was unchanged. We conclude that in the dog the liver, which remove
s anions at baseline, switches to release anions during early endotoxe
mia and may be a major site of acid production in early sepsis.