Characterization of the portal signal in a nonsteady hyperglycemic state in conscious dogs.
To characterize the "portal signal" in a nonsteady hyperglycemic state, the kinetic relationship between net hepatic glucose balance (NHGB) and either hepatic glucose load (HGL) or plasma insulin level was determined during glucose infusion using a catheter technique in 36 conscious dogs. Glucose was infused intraportally (Po group) and peripherally (Pe group) at 39, 56, and 83 micromol x kg(-1) x min(-1) over 2 h. There was a linear relationship between mean NHGB and either mean HGL or plasma insulin levels at each rate in either delivery (HGL: Po r = 0.99, Pe r = 0.95; insulin: Po r = 99, Pe r = 0.79). The threshold levels for net hepatic glucose uptake were 3.8 and 11.7 mmol/l for plasma glucose and 65 and 392 pmol/l for plasma insulin, respectively. The slope of the regression line against the abscissa was four times larger in portal than in peripheral delivery (HGL: Po 0.20 vs. Pe 0.05, P < 0.05; insulin: Po 0.19 vs. Pe 0.04, P < 0.05). These results suggest that the portal signal overrules the threshold of glucose for hepatic uptake by increasing hepatic extraction rate in a nonsteady hyperglycemic state.
Ogihara
N
N
Department of Endocrinology and Metabolism, Institute for Adult Diseases, Asahi Life Foundation, Tokyo 160-0023, Japan.
Ebihara
S
S
Kawamura
W
W
Okamoto
M
M
Sakai
T
T
Takiguchi
K
K
Morita
T
T
Uchida
R
R
Matsuyama
Y
Y
Hayashi
Y
Y
Arakawa
Y
Y
Kikuchi
M
M
D000818:Animals; D001158:Arteries; D001783:Blood Flow Velocity; D001786:Blood Glucose / Q000032:analysis / Q000378:metabolism; D004285:Dogs; D005260:Female; D005934:Glucagon / Q000097:blood; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism; D006943:Hyperglycemia / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D007700:Kinetics; D008099:Liver / Q000098:blood supply / Q000378:metabolism*; D008297:Male; D011169:Portal Vein; D015398:Signal Transduction
D001786:Blood Glucose; D007328:Insulin; D005934:Glucagon; D005947:Glucose