scholarly journals Glucose metabolism in the developing rat. Studies in vivo

1972 ◽  
Vol 127 (3) ◽  
pp. 521-529 ◽  
Author(s):  
Richard G. Vernon ◽  
Deryck G. Walker
Keyword(s):  
Glucose Metabolism ◽  
Turnover Rate ◽  
Relative Size ◽  
Specific Radioactivity ◽  
Liver Glycogen ◽  
Glucose Turnover ◽  
Newborn Rat ◽  
Old Rats ◽  
Developing Rat

1. The specific radioactivity of plasma d-glucose and the incorporation of 14C into plasma l-lactate, liver glycogen and skeletal-muscle glycogen was measured as a function of time after the intraperitoneal injection of d-[6-14C]glucose and d-[6-3H]glucose into newborn, 2-, 10- and 30-day-old rats. 2. The log of the specific radioactivity of both plasma d-[6-14C]- and d-[6-3H]-glucose of the 2-, 10- and 30-day-old rats decreased linearly with time for at least 60min after injection of labelled glucose. The specific radioactivity of both plasma d-[6-14C]- and d-[6-3H]-glucose of the newborn rat remained constant for at least 75min after injection. 3. The glucose turnover rate of the 30-day-old rat was significantly greater than (approximately twice) that of the 2- and 10-day-old rats. The relative size of both the glucose pool and the glucose space decreased with age. Less than 10% of the glucose utilized in the 2-, 10- and 30-day-old rats was recycled via the Cori cycle. 4. The results are discussed in relationship to the availability of dietary glucose and other factors that may influence glucose metabolism in the developing rat.

scholarly journals Gluconeogenesis from lactate in the developing rat. Studies in vivo

1972 ◽  
Vol 127 (3) ◽  
pp. 531-537 ◽  
Author(s):  
Richard G. Vernon ◽  
Deryck G. Walker
Keyword(s):  
Skeletal Muscle ◽  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Half Life ◽  
Specific Radioactivity ◽  
Liver Glycogen ◽  
Plasma Lactate ◽  
Old Rats ◽  
Developing Rat

1. The specific radioactivity of plasma l-lactate and the incorporation of 14C into plasma d-glucose, liver glycogen and skeletal-muscle glycogen were measured as a function of time after the intraperitoneal injection of l-[U-14C]lactate into 2-, 10- and 30-day-old rats. 2. Between 15 and 60min after the injection of the l-[U-14C]lactate, the specific radioactivity of plasma lactate decreased with a half-life of 20–33min in animals at all three ages. 3. At all times after injection examined, the specific radioactivity of plasma glucose of the 2- and 10-day-old rats was at least fourfold greater than that of the 30-day-old rats. 4. Although 14C was incorporated into liver glycogen the amount incorporated was always less than 5% of that present in plasma glucose. 5. The results are discussed with reference to the factors that may influence the rate of incorporation of 14C into plasma glucose, and it is concluded that the rate of gluconeogenesis in the 2- and 10-day-old suckling rat is at least twice that of the weaned 30-day-old animal.

scholarly journals Metabolism of glucose in hyper- and hypo-thyroid rats in vivo. Glucose-turnover values and futile-cycle activities obtained with 14C- and 3H-labelled glucose

1979 ◽  
Vol 182 (2) ◽  
pp. 565-575 ◽  
Author(s):  
F Okajima ◽  
M Ui
Keyword(s):  
Blood Glucose ◽  
Specific Radioactivity ◽  
Glucose Production ◽  
Liver Glycogen ◽  
Glucose Turnover ◽  
Futile Cycle ◽  
Futile Cycles ◽  
The Difference ◽  
Glucose Recycling

1. A trace amount of glucose labelled with 14C uniformly and with 3H at position 2, 3 or 6 was injected intravenously into starved rats to measure the turnover rate of blood glucose. 2. Reliable estimates were made based on the semilogarithmic plot of specific radioactivity of the glucose contained in whole blood samples taken from the tail vein. 3. Glucose turned over more rapidly in hyperthyroid and more slowly in hypothyroid than in euthyroid rats. The percentage contribution of glucose recycling (determined from the difference in replacement rates between [U-14C]glucose and [6-3H]glucose) to the glucose utilization increased on induction of hyperthyroidism. 4. Futile cycles between glucose and glucose 6-phosphate (determined from the difference between replacement rates of [2-3H]glucose and [6-3H]glucose) were activated and inactivated by induction of hyperthyroid and hypothyroid states respectively. 5. The hepatic content of glycogen was much lower in hyper- and hypo-thyroid than in euthyroid rats. The enhanced glucose production in hyperthyroid rats resulted from not only activationof hepatic gluconeogenesis but also diversion of the final product of gluconeogenesis from liver glycogen to blood glucose. In hypothyroidism, the inhibition of gluconeogensis led to suppression of both glucose production and glycogenesis in the liver.

scholarly journals Effect of L-alanine infusion on gluconeogenesis and ketogenesis in the rat in vivo

1978 ◽  
Vol 170 (3) ◽  
pp. 583-591 ◽  
Author(s):  
P T Ozand ◽  
W D Reed ◽  
R L Hawkins ◽  
J H Stevenson ◽  
J T Tildon ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Blood Glucose ◽  
Specific Radioactivity ◽  
Liver Glycogen ◽  
Fed State ◽  
Old Rats ◽  
Gluconeogenic Substrate

1. In 48 h-starved 6-week-old rats the 14C incorporation in vivo into blood glucose from a constant-specific-radioactivity pool of circulating [14c]actateconfirmed that lactate is the preferred gluconeogenic substrate. 2. Increasing the blood [alanine] to that occurrring in the fed state increased 14C incorporation into blood glucose 2.3-fold from [14c]alanine and 1.7-fold from [14c]lactate. 3. When the blood [alanine] was increased to that in the fed state, the 14C incorporation into liver glycogen from circulating [14c]alanine or [14c]lactate increased 13.5- and 1.7-fold respectively. 4. The incorporation of 14C into blood acetoacetate and 3-hydroxybutyrate from a constant-specific-radioactivity pool of circulating [14c]oleate was virtually abolished by increasing the blood [alanine] to that existing in the fed state. However, the [acetoacetate] remained unchanged, whereas [3-hydroxybutyrate] decreased, although less rapidly than did its radiochemical concentration. 5. It is concluded that during starvation in 6-week-old rats, the blood [alanine] appears to influence ketogenesis for circulating unesterfied fatty acids and inversely affects gluconeogenesis from either lactate or alanine. A different pattern of gluconeogenesis may exist for alanine and lactate as evidenced by comparative 14C incorporation into liver glycogen and blood glucose.

GLUT2 and hexokinase control proximodistal gradient of intestinal glucose metabolism in the newborn pig

1997 ◽  
Vol 272 (6) ◽  
pp. G1530-G1539 ◽  
Author(s):  
C. Cherbuy ◽  
B. Darcy-Vrillon ◽  
L. Posho ◽  
P. Vaugelade ◽  
M. T. Morel ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Glucose Transporter ◽  
Glucose Utilization ◽  
Specific Effect ◽  
Glucose Consumption ◽  
Utilization Rate ◽  
Glucose Turnover ◽  
Proximal Jejunum ◽  
A Site

We have reported previously that a high glycolytic capacity develops soon after birth in enterocytes isolated from suckling newborn pigs. In the present work, we investigated whether such metabolic changes could affect intestinal glucose utilization in vivo and examined possible variations in glucose metabolism along the small intestine. Glucose utilization by individual tissues was assessed using the 2-deoxyglucose technique. The overall glucose utilization rate was doubled in suckling vs. fasting 2-day-old pigs because of significantly higher rates in all tissues studied, except for the brain. In parallel, enterocytes were isolated from the proximal, medium, or distal jejunoileum of newborn vs. 2-day-old pigs and assessed for their capacity to utilize, transport, and phosphorylate glucose. Intestinal glucose consumption accounted for approximately 15% of glucose turnover rate in suckling vs. 8% in fasting pigs. Moreover, there was a proximal-to-distal gradient of glucose utilization in the intestinal mucosa of suckling pigs. Such a gradient was also evidenced on isolated enterocytes. The stimulation of both hexokinase activity (HK2 isoform) and basolateral glucose transporter (GLUT2), as observed in the proximal jejunum, could account for such a site-specific effect of suckling.

scholarly journals Glucose metabolism in the newborn rat. Hormonal effects in vivo

1973 ◽  
Vol 134 (4) ◽  
pp. 899-906 ◽  
Author(s):  
Keith Snell ◽  
Deryck G. Walker
Keyword(s):  
Cyclic Amp ◽  
Intraperitoneal Injection ◽  
Actinomycin D ◽  
Specific Radioactivity ◽  
Liver Glycogen ◽  
Newborn Rats ◽  
Dibutyryl Cyclic Amp ◽  
Lactate Formation ◽  
Glucose Formation

1. The concentrations of liver glycogen and plasma d-glucose were measured in caesarian-delivered newborn rats at time-intervals up to 3h after delivery after treatment of the neonatal rats with glucagon, dibutyryl cyclic AMP, cortisol or cortisol+dibutyryl cyclic AMP. Glycogenolysis was promoted by glucagon or dibutyryl cyclic AMP in the third hour after birth but not at earlier times. Cortisol and dibutyryl cyclic AMP together (but neither agent alone) promoted glycogenolysis in the second hour after birth, but no hormone combination was effective in the first postnatal hour. 2. The specific radioactivity of plasma d-glucose was measured as a function of time for up to 75 min after the intraperitoneal injection of d-[6-14C]glucose and d-[6-3H]glucose into newborn rats at delivery and after treatment with glucagon or actinomycin D. Glucagon-mediated hyperglycaemia at this time was due to an increased rate of glucose formation and a decreased rate of glucose utilization. Actinomycin D prevented glucose formation and accelerated the rate of postnatal hypoglycaemia. 3. The specific radioactivity of plasma l-lactate and the incorporation of 14C into plasma d-glucose was measured as a function of time after the intraperitoneal injection of l-[U-14C]lactate into glucagon- or actinomycin D-treated rats immediately after delivery. The calculated rates of lactate formation were unchanged by either treatment, but lactate utilization was stimulated by glucagon administration. Glucagon stimulated and actinomycin D diminished 14C incorporation into plasma d-glucose. 4. The factors involved in the initiation of glycogenolysis and gluconeogenesis in the rat immediately after birth are discussed.

Estimation of glucose turnover and recycling in rabbits using various [3H, 14C]glucose labels

1976 ◽  
Vol 230 (4) ◽  
pp. 1159-1162 ◽  
Author(s):  
A Dunn ◽  
J Katz ◽  
S Golden ◽  
M Chenoweth
Keyword(s):  
Glucose Metabolism ◽  
Transit Time ◽  
Phosphate Level ◽  
Glucose Turnover ◽  
Replacement Rate ◽  
Carbon Recycling ◽  
Futile Cycling ◽  
Mean Glucose

The glucose replacement rate, percent carbon recycling, mean glucose transit time, and the glucose mass were determined in fasted unanesthetized rabbits after administration of [2-3H,U-14C]-, [3-3H,U-14C]-, [5-3H,U-14C]- or [6-3H,U-14C]glucose using the procedures of Katz et al. (10). The glucose replacement rates and carbon recycling determined with [2-3H,U-14C] and [5-3H,U-14C]glucose are equivalent and greater than those obtained with [3-3H,U-14C]- and [6-3H,U-14C]glucose. Although the means of the glucose replacement rates and percent carbon recycling obtained using [3-3H,U-14C]- and [6-3H,U-14C]glucose are similar, greater variation resulted using the former tracer. Comparisons of detritiation rates and percent carbon recycling using [2-3H,U-14C]- and [6-3H,U-14C]glucose suggest that about 10% of tritium is lost from carbon 2 via futile cycling at the glucose 6-phosphate level. Similarly, comparisons of [5-3H,U-14C]- and [6-3H,U-14C]glucose metabolism suggest that about 10% of tritium lost from carbon 5 occurs via futile cycling at the fructose diphosphate level and/or via the transaldolase reaction. Our results indicate that [6-3H,U-14C]glucose is the more suitable tracer for determining the glucose replacement rate and carbon recycling in vivo.

Impact of in vivo fatty acid oxidation blockade on glucose turnover and muscle glucose metabolism during low-dose AICAR infusion

2006 ◽  
Vol 291 (5) ◽  
pp. E1131-E1140 ◽  
Author(s):  
Michael Christopher ◽  
Christian Rantzau ◽  
Zhi-Ping Chen ◽  
Rodney Snow ◽  
Bruce Kemp ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Glucose Metabolism ◽  
Fatty Acid Oxidation ◽  
Low Dose ◽  
Whole Body ◽  
Glucose Turnover ◽  
Acid Oxidation ◽  
Metabolic Clearance ◽  
The Impact

AMPK plays a central role in influencing fuel usage and selection. The aim of this study was to analyze the impact of low-dose AMP analog 5-aminoimidazole-4-carboxamide-1-β-d-ribosyl monophosphate (ZMP) on whole body glucose turnover and skeletal muscle (SkM) glucose metabolism. Dogs were restudied after prior 48-h fatty acid oxidation (FAOX) blockade by methylpalmoxirate (MP; 5 × 12 hourly 10 mg/kg doses). During the basal equilibrium period (0–150 min), fasting dogs ( n = 8) were infused with [3-3H]glucose followed by either 2-h saline or AICAR (1.5–2.0 mg·kg−1·min−1) infusions. SkM was biopsied at completion of each study. On a separate day, the same protocol was undertaken after 48-h in vivo FAOX blockade. The AICAR and AICAR + MP studies were repeated in three chronic alloxan-diabetic dogs. AICAR produced a transient fall in plasma glucose and increase in insulin and a small decline in free fatty acid (FFA). Parallel increases in hepatic glucose production (HGP), glucose disappearance (Rd tissue), and glycolytic flux (GF) occurred, whereas metabolic clearance rate of glucose (MCRg) did not change significantly. Intracellular SkM glucose, glucose 6-phosphate, and glycogen were unchanged. Acetyl-CoA carboxylase (ACC∼pSer221) increased by 50%. In the AICAR + MP studies, the metabolic responses were modified: the glucose was lower over 120 min, only minor changes occurred with insulin and FFA, and HGP and Rd tissue responses were markedly attenuated, but MCRg and GF increased significantly. SkM substrates were unchanged, but ACC∼pSer221 rose by 80%. Thus low-dose AICAR leads to increases in HGP and SkM glucose uptake, which are modified by prior FAox blockade.

scholarly journals Measurement of protein turnover in rat liver. Analysis of the complex curve for decay of label in a mixture of proteins

1976 ◽  
Vol 156 (3) ◽  
pp. 657-663 ◽  
Author(s):  
P J Garlick ◽  
J C Waterlow ◽  
R W Swick
Keyword(s):  
Rat Liver ◽  
Turnover Rate ◽  
Decay Curve ◽  
Specific Radioactivity ◽  
Liver Protein ◽  
Turnover Rates ◽  
A Value ◽  
Maximum Value ◽  
Single Exponential

The curve for decay of 14C in rat liver protein labelled by injection of NaH14CO3 was analysed to obtain the average turnover rate of mixed liver protein. Three different methods of analysis were used. (1) Unlike decay curves from homogeneous proteins, the curve did not fit a single exponential, but a good fit was obtained with three exponentials. By assuming that the mixture contained three major components with different turnover rates, the calculated value for the average turnover rate (k) was close to 40% per day. (2) k was also calculated from the area under the decay curve, a method which makes no assumptions about the number of proteins in the mixture. This method also gave a value close to 40% per day. (3) It was shown empirically, both by simulation of decay of label in model mixtures of protein and with the decay curve measured in vivo, that k can be calculated from the time taken for the specific radioactivity to fall to 10% of its maximum value. This is an advantage, since the other two methods require the decay curve to be measured over a much longer period of time.

scholarly journals Acute Antiapoptotic Effects of Hydrocortisone in the Hippocampus of Neonatal Rats

2013 ◽  
pp. 205-213 ◽  
Author(s):  
P. N. MENSHANOV ◽  
A. V. BANNOVA ◽  
V. V. BULYGINA ◽  
N. N. DYGALO
Keyword(s):  
Glucocorticoid Receptor ◽  
Dna Fragmentation ◽  
Hippocampal Formation ◽  
Hormone Treatment ◽  
Protein Levels ◽  
Apoptotic Protein ◽  
Proapoptotic Protein ◽  
Old Rats ◽  
Developing Rat

Natural glucocorticoid hydrocortisone was suggested as a potent substitution for dexamethasone in the treatment of bronchopulmonary dysplasia in neonates. The aim of this study was to investigate whether hydrocortisone is able to affect the expression of apoptotic genes and the intensity of naturally occurring cell death in the developing rat hippocampus. Hormone treatment decreased procaspase-3 and active caspase-3 levels as well as DNA fragmentation intensity in the hippocampal formation of one-week-old rats in 6 h after injection. These changes were accompanied by an upregulation of antiapoptotic protein Bcl-XL, while expression of proapoptotic protein Bax remained unchanged. The action of hydrocortisone was glucocorticoid receptor-independent, as the selective glucocorticoid receptor agonist dexamethasone did not affect either apoptotic protein levels or DNA fragmentation intensity in the hippocampal region. The data are the first evidences for in vivo antiapoptotic effects of hydrocortisone in the developing hippocampus.

Reliability of continuous tracer infusion for measuring glucose turnover rate in rainbow trout

1997 ◽  
Vol 200 (19) ◽  
pp. 2557-2563 ◽  
Author(s):  
F Haman ◽  
M Powell ◽  
JM Weber
Keyword(s):  
Rainbow Trout ◽  
Whole Blood ◽  
Hormonal Regulation ◽  
Turnover Rate ◽  
Glucose Production ◽  
Glucose Turnover ◽  
In Vivo Measurement ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Glucose Flux

Glucose plays a fundamental role in mammalian energetics but its contribution as a metabolic fuel is not well established for fish; the accurate in vivo measurement of glucose flux is essential to determine the importance of this substrate in the energy budget of teleosts. Therefore, the goal of the present study was to verify the reliability of the continuous tracer infusion method for estimating glucose turnover rate in rainbow trout Oncorhynchus mykiss. Our secondary goals were to determine whether glucose flux can be estimated more accurately from plasma or from whole-blood samples, and to obtain an estimate of renal glucose production. Continuous infusions of [6-3H]glucose were performed in hepatectomized and intact animals. In some hepatectomized individuals, liver glucose production was replaced by a pump infusing unlabelled glucose at a known rate. Renal glucose production was measured in hepatectomized fish where liver glucose production was not replaced, and it averaged 1.1±0.1µmolkg-1min-1 (mean ± s.e.m., N=5). Results show that glucose turnover rate is quantified accurately by continuous tracer infusion and that glucose flux can be estimated equally well from plasma (error of -0.7±4.9%) and from whole-blood (error of -5.7±2.9%) samples (means ± s.e.m., N=7). This study provides the first experimental validation of continuous tracer infusion in fish, and shows that this method could become a powerful tool to investigate hormonal regulation of glucose metabolism in live teleosts.

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