Uptake of lactate by the liver: effect of red blood cell carriage.
Multiple-indicator dilution experiments with labeled lactate were performed in the livers of anesthetized dogs. A mixture of (51)Cr-labeled erythrocytes, [(3)H]sucrose, and L-[1-(14)C]lactate or a mixture of (51)Cr-labeled erythrocytes, [(14)C]sucrose, and L-[2-(3)H]lactate was injected into the portal vein, and samples were obtained from the hepatic vein. Data were evaluated using a model comprising flow along sinusoids, exchange of lactate between plasma and erythrocytes and between plasma and hepatocytes, and, in the case of L-[1-(14)C]lactate, metabolism to H[(14)C]O(-)(3) within hepatocytes. The coefficient for lactate efflux from erythrocytes was 0.62 +/- 0.24 s(-1), and those for influx into and efflux from hepatocytes were 0.44 +/- 0.13 and 0.14 +/- 0.07 s(-1), respectively. The influx permeability-surface area product of the hepatocyte membrane for lactate (P(in)S, in ml x s(-1) x g(-1)) varied with total flow rate (F, in ml s(-1) x g(-1)) according to P(in)S = (3.1 +/- 0.5)F + (0.021 +/- 0.014). Lactate in plasma, erythrocytes, and hepatocytes was close to equilibrium, whereas lactate metabolism was rate limiting.
Goresky
C A
CA
McGill University Medical Clinic, Montreal General Hospital, Montreal H3G 1A4, Quebec, Canada H3A 2T5.
Bach
G G
GG
Simard
A
A
Schwab
A J
AJ
Bracht
A
A
D000085:Acetates / Q000097:blood / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002250:Carbon Radioisotopes; D002463:Cell Membrane Permeability; D002860:Chromium Radioisotopes; D004285:Dogs; D004912:Erythrocytes / Q000502:physiology*; D006503:Hepatic Veins / Q000502:physiology; D007700:Kinetics; D007773:Lactates / Q000097:blood / Q000378:metabolism*; D008099:Liver / Q000098:blood supply / Q000378:metabolism*; D008954:Models, Biological; D011169:Portal Vein / Q000502:physiology*; D013395:Sucrose / Q000097:blood / Q000378:metabolism; D014316:Tritium
D000085:Acetates; D002250:Carbon Radioisotopes; D002860:Chromium Radioisotopes; D007773:Lactates; D014316:Tritium; D013395:Sucrose