Assessment of Glucose Turnover in Normal Man with the Use of a Non-Radioactive Isotopically Labelled Preparation, [6,6-2H]Glucose, as Tracer

1982 ◽  
Vol 63 (5) ◽  
pp. 437-440 ◽  
Author(s):  
J. W. Haigh ◽  
D. G. Johnston ◽  
A. J. McCulloch ◽  
M. F. Laker ◽  
J. Welby ◽  
...  
Keyword(s):  
Gas Chromatography Mass Spectrometry ◽  
Glucose Turnover ◽  
Metabolic Clearance ◽  
Intravenous Bolus ◽  
Metabolic Clearance Rate ◽  
Glucose Kinetics ◽  
Radioactive Label ◽  
Normal Man ◽  
The Mean ◽  
Male Subjects

1. Glucose kinetics were assessed in seven normal adult male subjects by an intravenous bolus technique with the use of a non-radioactive isotopically labelled preparation, [6,6-2H]glucose, as tracer. Tracer enrichment in plasma was assessed by gas chromatography-mass spectrometry. For comparison five subjects also received a simultaneous intravenous bolus of [6-3H]glucose and kinetics were assessed by conventional means. 2. Administration of [6,6-2H]glucose did not alter circulating glucose or insulin concentrations. 3. Glucose turnover, assessed by the use of [6,6-2H]glucose, was 11·4 (±0·9) μmol min−1 kg−1 and 11·6 (±0·5) μmol min−1 kg−1 with [6-3H]glucose. The mean metabolic clearance rate of glucose was 2·3 (±0·3) ml min−1 kg−1 with both isotopically labelled tracers. Estimates of mean residence time, glucose pool and glucose space were also similar by each technique. 4. [6,6-2H]Glucose is therefore an effective tracer and allows investigation of glucose kinetics without administration of a radioactive label.

Glucoregulatory and hormonal responses to repeated bouts of intense exercise in normal male subjects

1991 ◽  
Vol 71 (3) ◽  
pp. 924-933 ◽  
Author(s):  
E. B. Marliss ◽  
E. Simantirakis ◽  
P. D. Miles ◽  
C. Purdon ◽  
R. Gougeon ◽  
...  
Keyword(s):  
Clearance Rate ◽  
Glucose Production ◽  
Glucose Turnover ◽  
Normal Male ◽  
Plasma Norepinephrine ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Early Recovery ◽  
Muscle Adaptations ◽  
Male Subjects

Glucose turnover and its regulation were studied during and after two identical bouts of intense exhaustive exercise separated by 1 h to define differences in response. Six lean young postabsorptive male subjects exercised at approximately 100% maximal O2 uptake (3.7 +/- 0.3 l/min) for 13.0 +/- 0.7 min for the first (EX1) and 13.2 +/- 0.8 min for the second (EX2) bout. Plasma glucose increased during EX1 and peaked at 7.0 +/- 0.6 mmol/l in early recovery but to 5.8 +/- 0.5 mmol/l (P less than 0.05) after EX2, and both the hyperglycemic and the hyperinsulinemic responses were less after EX2 (P less than 0.015, analysis of variance). The hyperglycemia was due to lesser increments in glucose utilization (Rd) (3-fold resting) than glucose production (Ra) (7-fold) toward exhaustion and for 7 min of recovery. The rise in Rd was more rapid (P less than 0.05) and metabolic clearance rate was greater during (P = 0.015) and from 9 to 60 min after EX2, and Ra also remained higher during recovery (P less than 0.05). Marked and similar increments in plasma norepinephrine (18-fold) and epinephrine (14-fold) occurred with both bouts. Plasma glucagon increments were small and not different. Therefore, 1) more circulating glucose was used with EX2, 2) greater metabolic clearance rate during and after EX2 suggests local muscle adaptations due to EX1, and 3) significant correlations (P less than 0.002) between plasma norepinephrine and Ra (r = 0.82) and Ra - Rd (r = 0.52) and between epinephrine and Ra (r = 0.71) and Ra - Rd (r = 0.48) suggest a major regulatory role for the catecholamine responses.

THE EFFECT OF EPINEPHRINE ON TESTOSTERONE PRODUCTION

1967 ◽  
Vol 55 (1) ◽  
pp. 184-192 ◽  
Author(s):  
Joseph Levin ◽  
Charles W. Lloyd ◽  
Julia Lobotsky ◽  
E. H. Friedrich
Keyword(s):  
Production Rate ◽  
Mean Value ◽  
Constant Infusion ◽  
Plasma Testosterone ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Testosterone Concentration ◽  
The Mean ◽  
Male Subjects ◽  
Double Isotope

ABSTRACT The metabolic clearance rate (MCR) and the production rate (PR) of testosterone were measured in four male subjects by the method of constant infusion of tritiated testosterone. The mean value of the MCR of 1161 ± 80 (SD) liters/24 hours was not altered by the infusion of epinephrine, at the rate of 0.466 mg per hour for three: hours. The plasma testosterone concentration was measured by the double isotope method of Riondel et al. (1963). Epinephrine significantly decreased this concentration (28%) and also the production rate (28%) The effect of epinephrine on plasma testosterone concentration was measured in six additional male subjects, and the results of the total of 10 subjects showed that there was a decrease of (28%) in the concentration. It was concluded that epinephrine significantly diminished the production rate of testosterone.

Effect of endurance training on glucose kinetics during exercise

1983 ◽  
Vol 244 (5) ◽  
pp. E505-E512 ◽  
Author(s):  
G. A. Brooks ◽  
C. M. Donovan
Keyword(s):  
Blood Glucose ◽  
Respiratory Exchange Ratio ◽  
Glucose Turnover ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Glucose Kinetics ◽  
Glucose Levels ◽  
Arterial Blood ◽  
Blood Glucose Levels ◽  
Glucose Flux

Control and endurance-trained rats received continuous infusions via jugular catheters of [U-14C]- and [6-3H]glucose under one of three conditions: rest (Re), running at 13.4 m/min (easy exercise, EE), or running at 26.8 m/min (hard exercise, HE). Arterial blood was sampled from carotid catheters. Blood glucose levels were not different between groups at rest (3.88 +/- 0.19 mM) or EE (4.32 +/- 0.35 mM). During HE, trained animals maintained blood glucose better (3.41 +/- 0.34 mM) than did untrained animals (3.03 +/- 0.42 mM). Respiratory exchange ratio (R) increased from rest (0.79 +/- 0.05) to exercise and was significantly lower in trained than in untrained animals during HE (0.87 +/- 0.02 vs. 0.93 +/- 0.03). Glucose turnover (Rt) calculated from [3H]glucose was not different between groups at rest (46.2 +/- 2.7 mumol x kg-1 x min-1). Turnover increased during EE to 91.5 +/- 7.5 vs. 72 +/- 8.5 mumol x kg-1 x min-1 in untrained and trained animals, respectively. During HE, Rt rose to 95.0 +/- 12.6 in trained animals but fell to 78.7 +/- 9.9 mumol x kg-1 x min-1 in untrained animals. The percentage of glucose flux oxidized increased from rest (44.0 +/- 6.8%) to exercise and was significantly lower in trained (73.7 +/- 4.3%) than in untrained animals (95.1 +/- 3.8%) during HE. Metabolic clearance rate increased from 12.5 +/- 0.8 in Re to 29.4 +/- 6.0 ml x min-1 x kg-1 in HE but did not differ between groups. Training improved glucose homeostasis during HE by increasing the glucose flux and by reducing the fraction of the flux lost to oxidation.

Glucose and lactate kinetics after endotoxin administration in dogs.

1977 ◽  
Vol 232 (2) ◽  
pp. E180 ◽  
Author(s):  
R R Wolfe ◽  
D Elahi ◽  
J J Spitzer
Keyword(s):  
Lactate Concentration ◽  
Constant Infusion ◽  
Glucose Turnover ◽  
Metabolic Clearance ◽  
Plasma Lactate ◽  
Metabolic Clearance Rate ◽  
Metabolic Substrate ◽  
E Coli ◽  
Lactate Kinetics ◽  
Plasma Lactate Concentration

We studied the effects of E. coli endotoxin on the glucose and lactate kinetics in dogs by means of the primed constant infusion of [6(-3)H] glucose and Na-L-(+)-[U-14C] lactate. The infusion of endotoxin induced a transient hyperglycemic level, followed by a steady fall in plasma glucose to hypoglycemic levels. The rate of appearance (Ra) and the rate of disappearance (Rd) of glucose were both significantly elevated (P less than .05) for 150 min after endotoxin, after which neither differed from the preinfusion value. The metabolic clearance rate of glucose was significantly elevated at all times 30 min postendotoxin. By 30 min postendotoxin, Ra and Rd of lactate, plasma lactate concentration, and the percent of glucose turnover originating from lactate were significantly elevated and remained so for the duration of the experiment. We concluded that after endotoxin hypoglycemia developed because of an enhanced peripheral uptake of glucose and a failure of the liver to maintain an increased Ra of glucose. We also concluded that lactate became an important precursor for gluconeogenesis and an important metabolic substrate.

INFUSIONS OF hFSH AND hLH IN NORMAL MEN

1976 ◽  
Vol 81 (1) ◽  
pp. 225-233 ◽  
Author(s):  
J. M. Kjeld ◽  
P. Harsoulis ◽  
S. F. Kuku ◽  
J. C. Marshall ◽  
B. Kaufman ◽  
...  
Keyword(s):  
Slow Component ◽  
Follicle Stimulating Hormone ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Average Value ◽  
Endogenous Production ◽  
Serial Serum ◽  
The Mean ◽  
Distribution Spaces ◽  
Normal Men

ABSTRACT Serial serum assays of immunoreactive FSH before, during and after a 4 h intravenous infusion of human follicle stimulating hormone (hFSH) in five healthy men revealed two disappearance rate constants with corresponding mean half-lives of 2.9 and 50.6 h. The mean distribution spaces calculated for the fast and slow component were 4.36 1 and 75.9 1 respectively. The average value for the metabolic clearance rate was 17.2 ml/min and for the endogenous production rate 50.9 mU/min. Two of the subjects had human luteinizing hormone (hLH) added in the infusions without the FSH kinetics changing.

Urine Electrolyte Response to 18-Hydroxy-11-Deoxycorticosterone in Normal Man

1977 ◽  
Vol 53 (5) ◽  
pp. 493-498 ◽  
Author(s):  
M. G. Nicholls ◽  
R. Fraser ◽  
G. Hay ◽  
P. Mason ◽  
B. Torsney
Keyword(s):  
Marked Effect ◽  
Plasma Concentrations ◽  
Urine Volume ◽  
Metabolic Clearance ◽  
Potassium Excretion ◽  
Metabolic Clearance Rate ◽  
Urine Ph ◽  
Urine Potassium ◽  
Normal Man ◽  
Plasma Half Life

1. To assess whether the adrenal corticosteroid 18-hydroxy-11-deoxycorticosterone [18-(OH)DOC] affects urine electrolyte excretion in normal man, seven male volunteers received 120 μg (353 nmol) intravenously in 1 h. This was compared with glucose (50 g/l; control) and aldosterone (80 μg, 222 nmol) infusions in the same subjects. 2. A definite though weak antinatriuretic response to 18-(OH)DOC was observed, whereas urine potassium excretion was not altered. Aldosterone increased urine potassium excretion and reduced sodium output. Urine pH was lowered by both corticosteroids, aldosterone in general having a more marked effect. Urine volume was not altered by 18-(OH)DOC. 3. Plasma concentrations of 18-(OH)DOC and aldosterone rose approximately tenfold during their respective infusions. Compared with that of aldosterone, the metabolic clearance rate of 18-(OH)DOC was slower and its plasma half-life was longer. 4. We have been able to demonstrate that 18-(OH)DOC has a definite, albeit weak antinatriuretic action in normal man, but whether or not this corticosteroid is capable of elevating the blood pressure in man remains to be shown.

METABOLIC CLEARANCE RATE, PRODUCTION RATE, AND MAMMARY UPTAKE AND METABOLISM OF PROGESTERONE IN COWS

1975 ◽  
Vol 66 (2) ◽  
pp. 239-247 ◽  
Author(s):  
R. B. HEAP ◽  
A. HENVILLE ◽  
J. L. LINZELL
Keyword(s):  
Production Rate ◽  
Clearance Rate ◽  
Jugular Vein ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Tracer Kinetic ◽  
The Mean ◽  
Jersey Cows ◽  
Conscious Animals ◽  
Uptake And Metabolism

SUMMARY Tracer kinetic techniques have been used to measure the production rate, metabolic clearance rate and mammary uptake of progesterone in six experiments on two Jersey cows. The cows were surgically prepared so that the carotid artery, jugular vein and mammary vein concentrations of progesterone, and udder blood flow, could be determined in conscious animals without anaesthesia or stress. The mean production rate of progesterone was 173 ± 23·3 (s.e.m.) μg/min, with values ranging from 80 to 276 μg/min in pregnancy. The metabolic clearance rate was 22·5 ± 2·0 1/min, or 0·21 ± 0·025 1/min/kg metabolic body weight. The mammary uptake of progesterone was low, 3·1 ± 1·1 μg/min, and udder uptake accounted for about 3% of progesterone production rate. During [3H]progesterone infusion, radioactivity was transferred from blood to milk, probably by diffusion down a concentration gradient. Progesterone accounted for more than 88% of the ether-soluble radioactivity recovered from milk.

Metabolic clearance rate in sheep of a met-enkephalin analogue estimated by radioimmunoassay

1982 ◽  
Vol 93 (3) ◽  
pp. 427-433 ◽  
Author(s):  
J. E. Bolton ◽  
J. H. Livesey ◽  
R. A. Donald
Keyword(s):  
Clearance Rate ◽  
Bolus Injection ◽  
Plasma Concentrations ◽  
Volume Of Distribution ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Time Intervals ◽  
Naturally Occurring ◽  
Specific Radioimmunoassay ◽  
The Mean

A sensitive and specific radioimmunoassay developed for measuring the met-enkephalin analogue d-ala2-met(0)5-ol-enkephalin (DAMME) was used to study the pharmacokinetics of DAMME in the circulation of sheep. Plasma concentrations of DAMME were measured at varying time-intervals after an intravenous bolus injection or following a constant intravenous infusion of the analogue. The mean metabolic clearance rate of DAMME was 2·8 ml/min per kg, the mean circulating half-life was 52 min and the mean volume of distribution was 190 ml/kg. The longer circulating time of the analogue when compared with that of naturally occurring met-enkephalin would appear to explain its prolonged analgesic effect.

Metabolic clearance rate of testosterone in male epileptic patients on anti-convulsant therapy

1991 ◽  
Vol 129 (3) ◽  
pp. 465-468 ◽  
Author(s):  
M. J. Wheeler ◽  
B. K. Toone ◽  
A. Dannatt ◽  
P. B. C. Fenwick ◽  
S. Brown
Keyword(s):  
Clearance Rate ◽  
Patient Population ◽  
Free Testosterone ◽  
Sex Hormone Binding Globulin ◽  
Total Testosterone ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Testosterone Concentration ◽  
The Mean ◽  
Low Testosterone

ABSTRACT There are several reports which state that male epileptics on anti-convulsant therapy have reduced sexual activity. We and others have shown that, although total testosterone is raised, the free testosterone concentration is reduced in this patient population. This could be a result of an increased metabolic clearance rate (MCR) of testosterone, inadequate secretion of LH to stimulate testosterone synthesis or inappropriately low testosterone production by the Leydig cells. We have examined these possibilities by measuring the MCR of testosterone in 15 male epileptics on anti-convulsant therapy. In this group of patients, the mean LH (9·3±5·9 IU/l) and sex-hormone binding globulin (SHBG) (54·5±22·9 nmol/l) concentrations were significantly greater than those of five normal control subjects (4·7±1·11 IU/l and 26·0 ±7·0 nmol/l respectively). Mean total testosterone concentrations of the two groups were not significantly different but the mean percentage of free testosterone and free testosterone concentration were significantly lower in the patient population (2·06±0·43 vs 2·98±0·27 and 0·56±1·1 vs 0·79±0·7 pmol/l). The MCR of testosterone was significantly lower in the patients (773±322 vs 1354±443 1/day) and showed a positive correlation with the percentage of free testosterone. Therefore, our results suggest that the lowered free testosterone in male epileptics on anti-convulsant therapy is not due to an increased MCR of testosterone. The increased LH concentration suggests primary hypogonadism. This, in turn, could be responsible for low free testosterone levels in the presence of normal testosterone. Journal of Endocrinology (1991) 129, 465–468

scholarly journals Effect of pregnancy on the metabolic clearance rate and the volume of distribution of oxytocin in the baboon

1998 ◽  
Vol 274 (5) ◽  
pp. E791-E795 ◽  
Author(s):  
Wlodzimierz B. Kowalski ◽  
Lubomir Diveky ◽  
Ramkrishna Mehendale ◽  
Michael Parsons ◽  
Laird Wilson
Keyword(s):  
Clearance Rate ◽  
Volume Of Distribution ◽  
Pharmacokinetic Parameters ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Arterial Access ◽  
Initial Dilution ◽  
Uterine Contractions ◽  
The Mean ◽  
Dilution Volume

Pharmacokinetic parameters of oxytocin (OT) metabolism were determined during the last third of pregnancy and again 4–8 wk after delivery in the baboon. Animals were placed on a tether system with venous and arterial access and a continuous monitoring of uterine contractions during gestation. Two methods of determining OT pharmacokinetics were utilized (bolus injection vs. continuous infusion). The metabolic clearance rate of OT as determined during the bolus trials ( n = 7) was 22.2 ± 1.5 ml ⋅ min−1 ⋅ kg−1in pregnancy and 16.3 ± 1.4 ml ⋅ min−1 ⋅ kg−1postpartum ( P < 0.05), respectively, and 23.7 ± 2.8 vs. 16.9 ± 3.7 ml ⋅ min−1 ⋅ kg−1( P < 0.05), respectively, as determined during the 1-h infusion trials ( n = 4). The initial dilution volume and the volume of distribution at steady state of OT after administration did not differ between pregnant and postpartum animals ( P > 0.05). The mean residence time (MRT) of OT was shorter during pregnancy, 7.7 ± 0.8 vs. 10.8 ± 1.2 min postpartum ( P < 0.05). In summary, OT metabolism during pregnancy in the baboon is characterized by 1) increased clearance rate (1.4-fold), 2) accelerated turnover due to the shorter MRT, and 3) unaltered distribution.

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