Portal vein caffeine infusion enhances net hepatic glucose uptake during a glucose load in conscious dogs.

Pencek RR, Battram D, Shearer J, James FD, Lacy DB, Jabbour K, Williams PE, Graham TE, Wasserman DH
J Nutr. 2004 134 (11): 3042-6

PMID: 15514273 · DOI:10.1093/jn/134.11.3042

We determined whether intraportal caffeine infusion, at rates designed to create concentrations similar to that seen with normal dietary intake, would enhance net hepatic glucose uptake (NHGU) during a glucose load. Dogs (n = 15) were implanted with sampling and infusion catheters as well as flow probes >16 d before the studies. After a basal sampling period, dogs were administered a somatostatin infusion (0-150 min) as well as intraportal infusions of glucose [18 micromol/(kg . min)], basal glucagon [0.5 ng/(kg . min)], and insulin [8.3 pmol/(kg . min)] to establish mild hyperinsulinemia. Arterial glucose was clamped at 10 mmol/L with a peripheral glucose infusion. At 80 min, either saline (Control; n = 7) or caffeine [1.5 micromol/(kg . min); n = 8] was infused into the portal vein. Arterial insulin, glucagon, norepinephrine, and glucose did not differ between groups. In dogs infused with caffeine, NHGU was significantly higher than in controls [21.2 +/- 4.3 vs. 11.2 +/- 1.6 micromol/(kg . min)]. Caffeine increased net hepatic lactate output compared with controls [12.5 +/- 3.8 vs. 5.5 +/- 1.5 micromol/(kg . min)]. These findings indicate that physiologic circulating levels of caffeine can enhance NHGU during a glucose load, and the added glucose consumed by the liver is in part converted to lactate.

MeSH Terms (25)

Alanine Animals Arteries Blood Glucose Caffeine Dogs Epinephrine Fatty Acids, Nonesterified Female Fructosephosphates Glucagon Glucose Glucose-6-Phosphate Glucose Clamp Technique Glycerol Glycogen Glycogen Phosphorylase Glycogen Synthase Infusions, Intravenous Insulin Lactic Acid Liver Male Norepinephrine Portal Vein

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