Use of an artificial oxygen carrier in isolated rat liver perfusion: first demonstration of net glucose uptake at physiological portal glucose concentrations using a hemoglobin-free perfusate.
A defect in isolated perfused rat-liver (IPRL) preparations has been proposed to explain discrepancies between in vivo and in vitro findings regarding hepatic glucose metabolism. The aim of the present study was to investigate whether a preparation of IPRL using a synthetic hemoglobin-free perfusate was capable of net glucose uptake and glycogen deposition at physiological portal substrate concentrations. Livers from fed anaesthetized rats were perfused in a recirculating system using a fluorocarbon emulsion as artificial oxygen carrier. Depending on the prevailing glucose concentration, livers exhibited net glucose uptake or release with a threshold value of 5.5-6.0 mM glucose. Net glucose uptake was associated with net glycogen deposition (+0.23 to +0.59 mumol C6 min-1 g-1). From 5.8 mM (n = 3) and 10.0 mM (n = 8), initial concentration glucose levels fell to 5.3 +/- 0.2 mM after 210 min (n = 3) and 6.3 +/- 0.9 mM after 120 min (n = 8), respectively. This was equivalent to a net glucose uptake of -0.16 and -0.45 mumol min-1 g-1. Anoxia reversibly switched hepatic glucose balance from net uptake (-0.42 mumol min-1 g-1) to release (+0.69 mumol min-1 g-1) followed by net uptake (-0.50 mumol min-1 g-1) after reinstitution of aerobic conditions. We conclude that the composition of perfusion media might play a pivotal role for studies of glucose metabolism in the isolated perfused rat liver. In our experimental model, using a hemoglobin-free synthetic medium, net glucose uptake was readily demonstrated at physiological portal substrate concentrations similar to the in vivo situation.
Plauth
M
M
Eberhard-Karls-Universität, Abteilung Innere Medizin I, Tübingen, Federal Republic of Germany.
Zimmermann
B
B
Raible
A
A
Vieillard-Baron
D
D
Bauder-Gross
D
D
Hartmann
F
F
D000332:Aerobiosis; D000818:Animals; D001802:Blood Substitutes / Q000494:pharmacology*; D005466:Fluorocarbons / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism* / Q000493:pharmacokinetics; D006003:Glycogen / Q000096:biosynthesis*; D000860:Hypoxia / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D010477:Perfusion; D011168:Portal System; D051381:Rats; D011919:Rats, Inbred Strains
D001802:Blood Substitutes; D005466:Fluorocarbons; D006003:Glycogen; D005947:Glucose; D010100:Oxygen