Characterization of the portal signal during 24-h glucose delivery in unrestrained, conscious rats

To characterize the "portal signal" during physiological glucose delivery, liver glycogen was measured in unrestrained rats during portal (Po) and peripheral (Pe) constant-rate infusion, with minimal differences in hepatic glucose load (HGL) and portal insulin between the delivery routes....

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Published inAmerican journal of physiology: endocrinology and metabolism Vol. 49; no. 6; pp. E932 - E940
Main Authors OGIHARA, N, KAWAMURA, W, KASUGA, K, HAYASHI, Y, ARAKAWA, H, KIKUCHI, M
Format Journal Article
LanguageEnglish
Published Bethesda, MD American Physiological Society 01.06.2004
Subjects
Biological and medical sciences
Blood
Delivery. Postpartum. Lactation
Fundamental and applied biological sciences. Psychology
Glucose
Gynecology. Andrology. Obstetrics
Insulin
Measurement techniques
Medical sciences
Rodents
Vertebrates: endocrinology
negative arterial- portal glucose gradients
Rat
Digestive system
Glycogen
Liver
Rodentia
hepatic glucose load
Biosynthesis
Glucose
Characterization
Vertebrata
nonsteady state
Mammalia
Synthesis
hepatic glycogen synthesis
Animal
Delivery
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Summary:To characterize the "portal signal" during physiological glucose delivery, liver glycogen was measured in unrestrained rats during portal (Po) and peripheral (Pe) constant-rate infusion, with minimal differences in hepatic glucose load (HGL) and portal insulin between the delivery routes. Hepatic blood flows were measured by Doppler flowmetry during open surgery. Changes in hepatic glucose, portal insulin, glucagon, lactate, and free fatty acid concentrations were generally similar in either delivery except for glucagon at 4 h. Hepatic glycogen, however, increased continuously in Po and was higher than Pe at 8 and 24 h, although it decreased to the level of Pe upon the removal of Po at 8 h. There was a near-linear relationship between hepatic glycogen and HGL in either delivery, with the slope being twice as high in Po and the intercepts converging to basal HGL. The hepatic response to Po did not alter upon 80% replacement by Pe. These results suggest that negative arterial-portal glucose gradients increase the rate of hepatic glycogen synthesis against the incremental HGL in an all-or-nothing mode. [PUBLICATION ABSTRACT]
ISSN:0193-1849
1522-1555