Human hepatic carbohydrate metabolism

1997 ◽  
Vol 38 (6) ◽  
pp. 998-1002 ◽  
Author(s):  
H. Ikehira ◽  
T. Obata ◽  
M. Koga ◽  
K. Yoshida

Purpose: Dynamic natural-abundance 13C MR spectroscopy (MRS) studies without proton decoupling were performed in the human liver using commercial 1.5 T MR equipment Material and Methods: A single tuned custom-made circular surface coil with an OD of 20 cm operating at 16.04 MHz was used for the 13C study. Seventy-five grams of glucose dissolved in water was administered for the natural-abundance 13C-MRS dynamic study which lasted for approximately 40 to 60 min. Data acquisition was broken into 20-min and 1.7-min blocks. Localized proton shimming with a whole-body coil was performed with sufficient volume to include the observing area of the surface coil; the line width of the water signal was less than 20 Hz Results and Conclusion: the glucose and glycogen spectra were clearly visible at 80 to 120 ppm after oral administration of the glucose solution. These data demonstrate that dynamic hepatic carbohydrate metabolism can be observed with commercially available MR equipment. Given that the human hepatic glycogen pool reaches maximum level within less than 10 min, this technique should provide a direct diagnosis of hepatic carbohydrate metabolic disorders

1996 ◽  
Vol 270 (1) ◽  
pp. E186-E191 ◽  
Author(s):  
K. F. Petersen ◽  
T. Price ◽  
G. W. Cline ◽  
D. L. Rothman ◽  
G. I. Shulman

Relative contributions of net hepatic glycogenolysis and gluconeogenesis to glucose production during the first 12 h of a fast were studied in 13 healthy volunteers by noninvasively measuring hepatic glycogen content using 13C nuclear magnetic resonance spectroscopy. Rates of net hepatic glycogenolysis were calculated by multiplying the change in liver glycogen content with liver volume determined by magnetic resonance imaging. Rates of gluconeogenesis were calculated as the difference between rates of glucose production determined with an infusion of [6,6-2H]-glucose and net hepatic glycogenolysis. At 6 P.M. a liquid mixed meal (1,000 kcal; 60% as glucose) was given, to which [2-2H]glucose was added to trace glucose absorption. Hepatic glycogen content was measured between 11 P.M. and 1 A.M. and between 3 and 6 A.M. At 11 P.M. the concentration was 470 mM and it decreased linearly during the night. The mean liver volume was 1.47 +/- 0.06 liters. Net hepatic glycogenolysis (5.8 +/- 0.8 mumol.kg body wt-1.min-1) accounted for, on average, 45 +/- 6% and gluconeogenesis for 55 +/- 6% of the rate of whole body glucose production (12.6 +/- 0.6 mumol.kg body wt-1.min-1). In conclusion, this study shows that, even early in the phase of the postabsorptive period when liver glycogen stores are maximal, gluconeogenesis contributes approximately 50% to hepatic glucose production.


1984 ◽  
Vol 56 (2) ◽  
pp. 334-337 ◽  
Author(s):  
J.R Alger ◽  
K.L Behar ◽  
D.L Rothman ◽  
R.G Shulman

1957 ◽  
Vol 190 (2) ◽  
pp. 239-242
Author(s):  
B. N. Spirtos ◽  
R. G. Stuelke ◽  
N. S. Halmi

Rats fed 10 gm of a commercial diet for 4–5 weeks and fasted for 24 hours showed less rise in liver glycogen and blood sugar levels in response to the injection of epinephrine than did ad libitum-fed-fasted rats. Gastrocnemius glycogen levels were found to be higher in underfed-fasted animals and fell to the same extent as in ad libitum fed-fasted animals when epinephrine was given. Blood lactate concentrations, however, rose less markedly in the underfed-fasted group. This may have been at least partly responsible for the diminished rise in hepatic glycogen and blood sugar.


2002 ◽  
Vol 364 (2) ◽  
pp. 361-368 ◽  
Author(s):  
Mary C. SUGDEN ◽  
Karen BULMER ◽  
Geoffrey F. GIBBONS ◽  
Brian L. KNIGHT ◽  
Mark J. HOLNESS

The aim of the present study was to determine whether peroxisome-proliferator-activated receptor-α (PPARα) deficiency disrupts the normal regulation of triacylglycerol (TAG) accumulation, hepatic lipogenesis and glycogenesis by fatty acids and insulin using PPARα-null mice. In wild-type mice, hepatic TAG concentrations increased (P<0.01) with fasting (24h), with substantial reversal after refeeding (6h). Hepatic TAG levels in fed PPARα-null mice were 2.4-fold higher than in the wild-type (P<0.05), increased with fasting, but remained elevated after refeeding. PPARα deficiency also impaired hepatic glycogen repletion (P<0.001), despite normal insulin and glucose levels after refeeding. Higher levels of plasma insulin were required to support similar levels of hepatic lipogenesis de novo (3H2O incorporation) in the PPARα-null mice compared with the wild-type. This difference was reflected by corresponding changes in the relationship between plasma insulin and the mRNA expression of the lipogenic transcription factor sterol-regulatory-element-binding protein-1c, and that of one of its known targets, fatty acid synthase. In wild-type mice, hepatic pyruvate dehydrogenase kinase (PDK) 4 protein expression (a downstream marker of altered fatty acid catabolism) increased (P<0.01) in response to fasting, with suppression (P<0.001) by refeeding. Although PDK4 up-regulation after fasting was halved by PPARα deficiency, PDK4 suppression after refeeding was attenuated. In summary, PPARα deficiency leads to accumulation of hepatic TAG and elicits dysregulation of hepatic lipid and carbohydrate metabolism, emphasizing the importance of precise control of lipid oxidation for hepatic fuel homoeostasis.


2009 ◽  
Vol 20 (6) ◽  
pp. 1366-1373 ◽  
Author(s):  
Taro Takahara ◽  
Thomas Kwee ◽  
Satoshi Kibune ◽  
Reiji Ochiai ◽  
Tetsuro Sakamoto ◽  
...  

1960 ◽  
Vol 198 (1) ◽  
pp. 33-36
Author(s):  
Joseph A. Ontko

Male, weanling rats were exposed to 500 r of whole-body x-irradiation and then fasted. Control rats were concurrently fasted. Ketonemia, ketonuria, hepatic glycogen, ketogenesis by liver slices and fatty acid oxidase activity of liver mitochondria were measured. A radiation-induced decrease in fasting ketonemia was observed. This decrease was mainly in the ß-hydroxybutyric acid fraction. Ketonuria was similar in both control and irradiated lots the 1st postirradiation day and lower in the irradiated lot during the 2nd day. Decreased ketonemia in the irradiated rats, which exhibited diuresis, was thus apparently not due to increased urinary excretion of ketone bodies. Ketogenesis by liver slices from irradiated rats was depressed. This indicated that an antiketogenic process contributed to the radiation-induced decrease in fasting ketonemia. Fatty acid oxidase activity of liver mitochondria isolated from control and irradiated rats was similar. Thus, rate-limiting fatty acid oxidizing enzymes were not altered by radiation under these conditions. This illustrates an apparent modifying effect of other cellular fractions on fatty acid oxidation in mitochondria.


1957 ◽  
Vol 192 (1) ◽  
pp. 30-32 ◽  
Author(s):  
Nancy G. Boucot ◽  
Warren R. Guild ◽  
John P. Merrill

To define areas of carbohydrate metabolism which might be altered in uremia, determinations of gastric and intestinal absorption of glucose and deposition of glycogen in the liver of 9 acutely uremic and 24 control rats were performed. Residual gastric and intestinal glucose contents and hepatic glycogen contents were determined 3 hours after glucose lavage in rats fasted for 24 hours. No statistically significant difference was observed in gastrointestinal absorption of glucose and in hepatic deposition of glycogen of the uremic and control animals.


2005 ◽  
Vol 185 (3) ◽  
pp. 750-755 ◽  
Author(s):  
Darren D. Brennan ◽  
Ciaran Johnston ◽  
Julie O'Brien ◽  
David H. Taylor ◽  
Carmel Cronin ◽  
...  

1973 ◽  
Vol 30 (9) ◽  
pp. 1395-1398 ◽  
Author(s):  
V. Bibor ◽  
C. Leray

Two radioisotopes (Na125I and thyroxine125I) were used to investigate thyroid function in Perca flavescens. In the thyroid, if the hormonal fraction is very small (4% of total radioactive thyroid components, 5 days after injection of Na125I) the variation of this fraction with time suggests the existence of a rapid turnover of hormones (maximum level before 24 hr). The rapid incorporation of iodine into iodotyrosine compounds by the thyroid (60% of MIT + DIT after 12 hr) also suggests the involvement of a very important biosynthetic activity. At peripheral levels the rapid metabolism of T4125I ([Formula: see text] in the blood) confirms this view. In the plasma, the level of labelled hormones goes through two maxima followed (48 hr after injection of Na125I) by a steady increase. The second maximum observed is probably due to the release of thyroid hormones into the blood, but the first (6 hr after injection of Na125I) cannot be related to any known physiological process in fishes. The half-life of 125I in the plasma is the same as that in the whole body (4 days).


2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Laura H. Namisnak ◽  
Sepideh Khoshnevis ◽  
Kenneth R. Diller

Abstract The objective of this study was to test the feasibility of selective thermal stimulation (STS) as a method to upregulate glabrous skin blood flow. STS is accomplished by mild surface heating along the spinal cord. Four healthy subjects were tested in this study. Each participated in a control experiment and an intervention experiment (STS). Both experiments included establishing a maximum level of vasodilation, considered unique to a subject on a test day, and then cooling to a maximum level of vasoconstriction. Perfusion was measured by a laser Doppler flow probe on the index fingertip. The percent of perfusion in the range of minimum to maximum was the primary outcome variable. The data were fit to a linear mixed effects model to determine if STS had a significant influence on perfusion during whole body cooling. STS had a statistically significant effect on perfusion and increased glabrous skin blood flow by 16.3% (P < 0.001, CI (13.1%, 19.5%)) as skin temperature was decreased. This study supports the theory that STS improves the heat exchanger efficiency of palmar and plantar surfaces by increasing the blood flow.


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