scholarly journals Glucose metabolism in the newborn rat. Temporal studies in vivo

1973 ◽  
Vol 132 (4) ◽  
pp. 739-752 ◽  
Author(s):  
Keith Snell ◽  
Deryck G. Walker
Keyword(s):  
Intraperitoneal Injection ◽  
Glucose Utilization ◽  
Ketone Bodies ◽  
Post Partum ◽  
Specific Radioactivity ◽  
Liver Glycogen ◽  
Uterine Environment ◽  
Lactate Formation ◽  
Lactate Utilization

1. The concentrations of plasma d-glucose, l-lactate, free fatty acids and ketone bodies and of liver glycogen were measured in caesarian-delivered newborn rats at time-intervals up to 4h after delivery. Glucose and lactate concentrations decreased markedly during the first hours after delivery, but there was a delay of 60–90min before significant glycogen mobilization occurred. 2. The specific radioactivity of plasma d-glucose was measured as a function of time for up to 75min after the intraperitoneal injection of d-[6-14C]glucose and d-[6-3H]glucose into caesarian-delivered rats at 0, 1 and 2h after delivery. Calculations revealed that there was an appreciable rate of glucose formation at all ages studied, but immediately after delivery this was exceeded by the rate of glucose utilization. Around 2h post partum the rate of glucose utilization decreased dramatically and this coincided with a reversal of the immediately postnatal hypoglycaemia. 3. The specific radioactivity of plasma l-lactate and the incorporation of 14C into plasma d-glucose and liver glycogen was measured as a function of time after the intraperitoneal injection of l-[U-14C]lactate into rats immediately after delivery. The logarithm of the specific radioactivity of plasma l-[U-14C]lactate decreased linearly with time for at least 60min after injection and the calculated rate of lactate utilization exceeded the rate of lactate formation. 4. 14C incorporation into plasma d-glucose was maximal from 30–60min after injection of l-[U-14C]lactate and the amount incorporated at 60min was 23% of that present in plasma lactate. Although 14C was also incorporated into liver glycogen the amount was always less than 3% of that present in plasma glucose. 5. The results are discussed in relationship to the adaptation of the newly born rat to the extra-uterine environment and the possible involvement of gluconeogenesis at this time before feeding is established.

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.

scholarly journals Oestradiol inhibits collagen breakdown in the involuting rat uterus

1972 ◽  
Vol 127 (4) ◽  
pp. 705-713 ◽  
Author(s):  
Janet N. Ryan ◽  
J. Frederick Woessner
Keyword(s):  
Cathepsin D ◽  
Density Gradient Centrifugation ◽  
Post Partum ◽  
Gradient Centrifugation ◽  
Specific Radioactivity ◽  
Rat Uterus ◽  
Oestradiol Treatment ◽  
Cathepsin D Activity ◽  
Stimulation Of

1. The earlier observation (Woessner, 1969) of oestradiol inhibition of collagen breakdown is confirmed and extended. Administration of 100μg of oestradiol-17β/day to parturient rats strongly inhibits the loss of collagen from the involuting uterus. Three experiments show that this effect is due to an inhibition of collagen degradation rather than to a stimulation of collagen synthesis. 2. Uterine collagen was labelled with hydroxy[14C]-proline by the administration of [14C]proline near the end of pregnancy. By 3 days post partum, control uteri lost 83% of their collagen and 90% of their hydroxy[14C]proline. Uteri from oestradiol-treated rats lost only 50% of both total and labelled hydroxyproline, with no decrease in the specific radioactivity of the hydroxyproline. 3. Incorporation of [14C]proline into uterine collagen hydroxyproline in vivo was not affected by oestradiol treatment. 4. Urinary excretion of hydroxyproline was increased in post-partum control rats and decreased in oestradiol-treated rats. 5. An enzyme capable of cleaving 4-phenylazobenzyloxycarbonyl-l-prolyl-l-leucylglycyl- l-prolyl-d-arginine (a substrate for clostridial collagenase) increased in activity in the post-partum uterus and was unaffected by oestradiol treatment. 6. Uterine homogenates digested uterine collagen extensively at pH3.2. This digestion was unaffected by the oestradiol treatment. 7. Lysosomal fractions prepared by density-gradient centrifugation of uterine homogenates contained coincident peaks of cathepsin D activity and peptide-bound hydroxyproline. The cathepsin D and hydroxyproline contents of this peak were unaffected by oestradiol treatment.

scholarly journals The effects of amylin on carbohydrate metabolism in skeletal muscle in vitro and in vivo

1990 ◽  
Vol 269 (1) ◽  
pp. 19-23 ◽  
Author(s):  
B Leighton ◽  
E Foot
Keyword(s):  
Glucose Utilization ◽  
Glycogen Synthesis ◽  
Intraperitoneal Administration ◽  
Muscle Preparation ◽  
Glucose Incorporation ◽  
Rat Soleus Muscle ◽  
Lactate Formation ◽  
Human Amylin

1. The effects of synthetic human amylin on basal and insulin-stimulated (100 and 1000 microunits/ml) rates of lactate formation, glucose oxidation and glycogen synthesis were measured in the isolated rat soleus muscle preparation incubated in the presence of various concentrations of glucose (5, 11 and 22 mM). 2. The rate of glucose utilization was increased by about 2-fold by increasing the glucose concentration from 5 to 22 mM. 3. Synthetic human amylin (10 nM) significantly inhibited (by 46-56%) glycogen synthesis, irrespective of the concentration of insulin or glucose present in the incubation medium. 4. Amylin (10 nM) did not affect insulin-stimulated rates of 2-deoxy[3H]glucose transport and phosphorylation. 5. Intraperitoneal administration of insulin (100 micrograms/kg) to rats in vivo stimulated the rate of [U-14C]glucose incorporation into glycogen in the diaphragm by about 80-fold. This rate was decreased (by 28%) by co-administration of amylin (66 micrograms/kg).

scholarly journals Studies in lipogenesis in vivo. Fatty acid and cholesterol synthesis during starvation and re-feeding

1966 ◽  
Vol 101 (3) ◽  
pp. 811-818 ◽  
Author(s):  
GR Jansen ◽  
ME Zanetti ◽  
CF Hutchison
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Intraperitoneal Injection ◽  
Cholesterol Synthesis ◽  
Liver Glycogen ◽  
Acid Synthesis ◽  
Tracer Dose ◽  
Intraperitoneal Dose

1. Lipogenesis in vivo has been studied in mice given a 250mg. meal of [U-(14)C]glucose (2.5muc) or given an intraperitoneal injection of 25mug. of [U-(14)C]glucose (2.0muc). 2. The ability to convert a [U-(14)C]glucose meal into fatty acid was not significantly depressed by 6-7hr. of starvation. In contrast, incorporation of (14)C into fatty acid in the liver after the intraperitoneal dose of [(14)C]glucose was depressed by 80% and by more than 90% by 1 and 2hr. of starvation respectively. Carcass fatty acid synthesis from the [U-(14)C]glucose meal was not depressed by 12hr. of starvation, whereas from the tracer dose of [U-(14)C]glucose the depression in incorporation was 80% after 6hr. of starvation. 3. Re-feeding for 3 days, after 3 days' starvation, raised fatty acid synthesis and cholesterol synthesis in the liver fivefold and tenfold respectively above the levels in non-starved control mice. These increases were associated with an increased amount of both fatty acid and cholesterol in the liver. 4. After 18hr. of starvation incorporation of a [U-(14)C]glucose meal into carcass and liver glycogen were both increased threefold.

Conceptus development in vivo, endometrial and conceptus protein release in vitro following blastocyst transfer to ewes induced to ovulate at 28 days post-partum

1993 ◽  
Vol 5 (2) ◽  
pp. 191 ◽  
Author(s):  
JM Wallace ◽  
RP Aitken ◽  
MA Cheyne
Keyword(s):  
Binding Sites ◽  
Post Partum ◽  
Oxytocin Receptor ◽  
Blastocyst Transfer ◽  
Receptor Density ◽  
Conceptus Development ◽  
Uterine Environment ◽  
Transfer Procedures

The use of laparoscopic insemination to deposit semen into the tip of the uterine horn ensures fertilization in ewes induced to ovulate at 3-5 weeks post-partum. Acceptable pregnancy rates are achieved if embryos from post-partum donors are transferred to a normal uterine environment yet embryos rarely survive when transferred or returned to a post-partum uterus. Blastocyst transfer procedures were developed to test whether the post-partum uterus can support conceptus development during the period of rapid growth coincident with the maternal recognition of pregnancy. In Experiment 1, the efficiency of the blastocyst transfer procedure was determined using control ewes > 150 days post-partum. Eight of nine recipient ewes established pregnancies and 75% of blastocysts survived to term. In Experiment 2, blastocysts were transferred to control (n = 12) or post-partum (n = 10) recipients that had been induced to ovulate 28 days after lambing during the breeding season. Conceptus development was assessed 96 h after blastocyst transfer on Day 15 of the cycle. At this time, conceptus mass in the seven post-partum ewes which remained pregnant was generally lower than in the 11 corresponding control ewes. Conceptus and endometrial tissues were cultured separately for a further 24 h in vitro in the presence of [3H]leucine to determine production of oTP-1 and the pregnancy-specific endometrial protein p70 respectively. Oxytocin binding sites were measured in endometrial tissue. Following 96 h culture in a post-partum uterus the conceptus retained its competence to synthesize and secrete ovine trophoblast protein 1 (oTP-1) in vitro. However, despite normal oTP-1 production the conceptus tissue failed to completely suppress endometrial oxytocin receptor binding. The negative correlation between p70 production and oxytocin receptor density implies a possible role for this protein in the suppression of oxytocin receptor synthesis required to prevent luteolysis in pregnant ewes.

scholarly journals Activities of hexokinase, phosphofructokinase, 3-oxo acid coenzyme A-transferase and acetoacetyl-coenzyme A thiolase in nervous tissue from vertebrates and invertebrates

1973 ◽  
Vol 134 (1) ◽  
pp. 97-101 ◽  
Author(s):  
P. H. Sugden ◽  
E. A. Newsholme
Keyword(s):  
Nervous Tissue ◽  
Ketone Body ◽  
Glucose Utilization ◽  
Coenzyme A ◽  
Ketone Bodies ◽  
Animal Kingdom ◽  
Coa Transferase ◽  
Utilization Pathway ◽  
The Brain

1. The maximum activities of hexokinase and phosphofructokinase in nervous tissue from 18 different animals from different phyla range from 5.1 to 17.6 and from 24.0μmol/min per g fresh wt. respectively. In any one tissue the activities of these two enzymes are, in general, very similar. The rate of glucose utilization by the brain in vivo is much lower than the activities of hexokinase or phosphofructokinase. It is suggested that the high activities of these enzymes indicate a capacity for glycolysis which may be used by the brain during hypoxia or during conditions of extreme neuronal activity. 2. The activities of 3-oxo acid CoA-transferase and acetoacetyl-CoA thiolase in the nervous tissues range from 1.1 to 15.3 and from 0.7 to 4.5μmol/min per g fresh wt. respectively. Unfortunately the activities of these enzymes cannot be used to estimate maximal flux through the ketone-body-utilization pathway, since they may catalyse reactions that are close to equilibrium. Nonetheless, the presence of these enzymes in nervous tissue from a large variety of animals suggests that the importance of ketone bodies as a fuel for nervous tissue may be widespread in the animal kingdom.

CARBOHYDRATE METABOLISM IN HYPOTHERMIC RATS AND HAMSTERS

1962 ◽  
Vol 40 (10) ◽  
pp. 1427-1438 ◽  
Author(s):  
J. M. Maur ◽  
D. M. McComiskey ◽  
J. W. Haynes ◽  
J. R. Beaton
Keyword(s):  
Lactic Acid ◽  
Pyruvic Acid ◽  
Glucose Utilization ◽  
Ketone Bodies ◽  
Intraperitoneal Administration ◽  
Liver Glycogen ◽  
Progressive Increase ◽  
Glycogen Level ◽  
Apparent Decrease ◽  
Fasted Rats

Unanesthetized female animals were cooled without artifical ventilation in cylindrical screen cages under ice until the desired rectal temperature was attained. When fasted rats are cooled 15 minutes after the intraperitoneal administration of either glucose or sodium pyruvate, there is an impaired utilization of the glucose but not of the pyruvate. Rate of decrease of liver glycogen formed from administered glucose was not affected. The elevated level of blood lactic acid typical of hypothermic rats was further elevated by administration of pyruvate but not of glucose, suggesting increased production of lactic acid via pyruvic acid. Glucose utilization patterns of hamsters (hibernators) and rats (non-hibernators) were similar during hypothermia. In non-fasted rats rendered hypothermic there is a progressive increase in blood level of glucose accompanied by an initial decrease in liver glycogen level. Subsequent to this decrease in liver glycogen level, there is a marked increase in the plasma level of ketone bodies. It is concluded that although in hypothermia there is an impairment in glucose utilization, this probably represents decreased oxidative metabolism of carbohydrate, there being no apparent decrease in the formation of lactic acid via pyruvic acid. From the results of experiments with insulin- and alloxan-treated rats, it is concluded that metabolic alterations of hypothermia in rats may be modified in degree but are not eliminated by a prior state of diabetes or by prior administration of insulin.

scholarly journals Effects in vivo of food deprivation and 3-mercaptopicolinate in the glycogen-storage-disease (gsd/gsd) rat

1985 ◽  
Vol 231 (3) ◽  
pp. 755-759 ◽  
Author(s):  
D G Clark ◽  
M Brinkman ◽  
S D Neville ◽  
W D Haynes
Keyword(s):  
Blood Glucose ◽  
Food Deprivation ◽  
Intraperitoneal Injection ◽  
Storage Disease ◽  
Liver Glycogen ◽  
Glycogen Storage ◽  
Hepatic Glycogen ◽  
Glycogen Stores ◽  
Female Control

Intraperitoneal injection of 3-mercaptopicolinate into 24 h-food-deprived 27-week-old female control (GSD/GSD) rats lowered the concentration of circulating glucose by 66%, but glycerol and lactate concentrations were increased up to 3- and 4-fold respectively. In phosphorylase b kinase-deficient (gsd/gsd) rats the corresponding changes for blood glucose, lactate and glycerol were half those observed in the controls. Although the concentration of liver glycogen (approx. 12%, w/w) in the gsd/gsd rats was not altered during food deprivation, total hepatic glycogen was decreased by 17%. It is suggested that the gradual breakdown of the extensive hepatic glycogen stores during starvation assists in the maintenance of normoglycaemia in the gsd/gsd rat.

scholarly journals Lactase phlorhizin hydrolase turnover in vivo in water-fed and colostrum-fed newborn pigs

1996 ◽  
Vol 320 (3) ◽  
pp. 735-743 ◽  
Author(s):  
Mary A. DUDLEY ◽  
Douglas G. BURRIN ◽  
Andrea QUARONI ◽  
Judy ROSENBERGER ◽  
Gary COOK ◽  
...  
Keyword(s):  
Post Partum ◽  
Specific Radioactivity ◽  
Experimental Treatment ◽  
Synthesis Rate ◽  
Jejunal Mucosa ◽  
Treatment Groups ◽  
Newborn Pigs ◽  
The Absolute ◽  
Absolute Synthesis

We have estimated the synthesis rates in vivo of precursor and brush-border (BB) polypeptides of lactase phlorhizin hydrolase (LPH) in newborn pigs fed with water or colostrum for 24 h post partum. At the end of the feeding period, piglets were anaesthetized and infused intravenously for 3 h with l-[4-3H]-phenylalanine. Blood and jejunal samples were collected at timed intervals. The precursor and BB forms of LPH were isolated from jejunal mucosa by immunoprecipitation followed by SDS/PAGE, and their specific radioactivity in Phe determined. The kinetics of precursor and BB LPH labelling were analysed by using a linear compartmental model. Immunoisolated LPH protein consisted of five polypeptides [high-mannose LPH precursor (proLPHh), complex glycosylated LPH precursor (proLPHc), intermediate complex glycosylated LPH precursor (proLPHi) and two forms of BB LPH]. The fractional synthesis rate (Ks) of proLPHh and proLPHc (approx. 5%/min) were the same in the two groups but the absolute synthesis rate (in arbitrary units, min-1) of proLPHh in the colostrum-fed animals was twice that of the water-fed animals. The Ks values of proLPHi polypeptides were significantly different (water-fed, 3.89%/min; colostrum-fed, 1.6%/min), but the absolute synthesis rates did not differ. The Ks of BB LPH was not different between experimental treatment groups (on average 0.037%/min). However, the proportion of newly synthesized proLPHh processed to BB LPH was 48% lower in colostrum-fed than in water-fed animals. We conclude that in neonatal pigs, the ingestion of colostrum stimulates the synthesis of proLPHh but, at least temporarily, disrupts the processing of proLPH polypeptides to the BB enzyme.

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