Nonhepatic response to portal glucose delivery in conscious dogs.
The glycemic and hormonal responses and net hepatic and nonhepatic glucose uptakes were quantified in conscious 42-h-fasted dogs during a 180-min infusion of glucose at 10 mg. kg(-1). min(-1) via a peripheral (Pe10, n = 5) or the portal (Po10, n = 6) vein. Arterial plasma insulin concentrations were not different during the glucose infusion in Pe10 and Po10 (37 +/- 6 and 43 +/- 12 microU/ml, respectively), and glucagon concentrations declined similarly throughout the two studies. Arterial blood glucose concentrations during glucose infusion were not different between groups (125 +/- 13 and 120 +/- 6 mg/dl in Pe10 and Po10, respectively). Portal glucose delivery made the hepatic glucose load significantly greater (36 +/- 3 vs. 46 +/- 5 mg. kg(-1). min(-1) in Pe10 vs. Po10, respectively, P < 0.05). Net hepatic glucose uptake (NHGU; 1.1 +/- 0. 4 vs. 3.1 +/- 0.4 mg. kg(-1). min(-1)) and fractional extraction (0. 03 +/- 0.01 vs. 0.07 +/- 0.01) were smaller (P < 0.05) in Pe10 than in Po10. Nonhepatic (primarily muscle) glucose uptake was correspondingly increased in Pe10 compared with Po10 (8.9 +/- 0.4 vs. 6.9 +/- 0.4 mg. kg(-1). min(-1), P < 0.05). Approximately one-half of the difference in NHGU between groups could be accounted for by the difference in hepatic glucose load, with the remainder attributable to the effect of the portal signal itself. Even in the absence of somatostatin and fixed hormone concentrations, the portal signal acts to alter partitioning of a glucose load among the tissues, stimulating NHGU and reducing peripheral glucose uptake.
Moore
M C
MC
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0615, USA. genie.moore@mcmail.vanderbilt.edu
Hsieh
P S
PS
Neal
D W
DW
Cherrington
A D
AD
D000818:Animals; D003243:Consciousness; D004285:Dogs; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005934:Glucagon / Q000097:blood; D005947:Glucose / Q000493:pharmacokinetics*; D005990:Glycerol / Q000097:blood; D006503:Hepatic Veins / Q000502:physiology; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology; D019344:Lactic Acid / Q000097:blood; D008099:Liver / Q000098:blood supply* / Q000378:metabolism*; D008102:Liver Circulation / Q000502:physiology; D008297:Male; D011169:Portal Vein / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology
D005230:Fatty Acids, Nonesterified; D007328:Insulin; D019344:Lactic Acid; D005934:Glucagon; D005947:Glucose; D005990:Glycerol