SECRETION OF THE ANDROGENS IN THE MALE GUINEA-PIG DURING THE PERINATAL PERIOD

1978 ◽  
Vol 89 (4) ◽  
pp. 770-779 ◽  
Author(s):  
G. Pelardy ◽  
P. Delost
Keyword(s):  
Critical Period ◽  
Vas Deferens ◽  
Perinatal Period ◽  
Plasma Testosterone ◽  
Metabolic Clearance ◽  
Similar Increase ◽  
Metabolic Clearance Rate ◽  
Target Organs ◽  
Peripheral Metabolism ◽  
Androgen Levels

ABSTRACT Plasma and testicular testosterone, androstenedione and dihydrotestosterone concentrations have been estimated by radioimmunoassay in the male foetus and newborn guinea-pigs between day 62 of pregnancy to day 12 of post-natal life. The prenatal period is characterized by low plasma androgen levels and high testosterone and androstenedione testicular content. After birth there is a peak of plasma testosterone concentration on day 3 concomitant with a release of testicular androgens; no similar increase of androstenedione or DHT is observed in plasma. This peak in plasma testosterone is testis dependent because it disappears after castration; it is also light dependent at birth. The investigations on testosterone and androstenedione peripheral metabolism have shown that day 3 after parturition is a "critical period" in the evolution of the metabolic clearance rate, the production rate and the conversion rate of these two androgens. The neonatal increase in plasma testosterone may be accounted for by the variations in these metabolic parameters and may have an influence upon certain sexual target organs, especially upon the vas deferens, the androgens content of which increases during the same "critical period".

Peripheral metabolism of testosterone during the annual reproductive cycle in the male hedgehog, a hibernating mammal

1983 ◽  
Vol 61 (12) ◽  
pp. 2849-2855 ◽  
Author(s):  
M. Saboureau ◽  
J. Boissin
Keyword(s):  
Activity Period ◽  
Plasma Testosterone ◽  
Injection Technique ◽  
Metabolic Clearance ◽  
Annual Reproductive Cycle ◽  
Endocrine Activity ◽  
Testosterone Levels ◽  
High Level ◽  
Peripheral Metabolism ◽  
Resting Period

The seasonal cycle of plasma testosterone levels in hedgehogs of midwestern France shows large variations and different successive sequences: a resting period in autumn, an increase during winter in January, continued high levels from midwinter to midsummer that are characterized by an important spring peak, a regular decrease in May–June, a shorter but regular summer peak, and an involution beginning at the end of summer. To elucidate (i) the increase of plasma testosterone levels in January during hibernation and (ii) the regular decrease of plasma testosterone levels in May–June during the activity period, the seasonal cycles of metabolic clearance and production rates of testosterone were studied, using [3H]testosterone in a single injection technique. The rate of peripheral metabolism of testosterone was reduced in autumn but increased in January during hibernation, simultaneously with the endocrine activity of the testis; it was maximum in February–March, then fluctuated but stayed at a high level during spring and summer, and decreased in September. In these hedgehogs there is a clear annual cycle of testosterone production with two maxima, and only the decrease of plasma testosterone levels observed in June can be explained by an increase of the metabolic clearance rate.

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.

Comparative metabolic clearance rate, volume of distribution and plasma half-life of human β-lipotropin and acth

Life Sciences ◽  
1978 ◽  
Vol 23 (23) ◽  
pp. 2323-2330 ◽  
Author(s):  
Anthony S. Liotta ◽  
Choh Hao Li ◽  
George C. Schussler ◽  
Dorothy T. Krieger
Keyword(s):  
Clearance Rate ◽  
Half Life ◽  
Volume Of Distribution ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Plasma Half Life

scholarly journals The Renin-Angiotensin System in Conscious Newborn Sheep: Metabolic Clearance Rate and Activity

2007 ◽  
Vol 61 (6) ◽  
pp. 681-686 ◽  
Author(s):  
Sithembiso C Velaphi ◽  
Kevin Despain ◽  
Timothy Roy ◽  
Charles R Rosenfeld
Keyword(s):  
Clearance Rate ◽  
Renin Angiotensin System ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Angiotensin System ◽  
Renin Angiotensin

ANDROGEN METABOLISM IN CONGENITAL ADRENAL HYPERPLASIA DUE TO 11 β-HYDROXYLASE DEFICIENCY

PEDIATRICS ◽  
1969 ◽  
Vol 44 (2) ◽  
pp. 201-208
Author(s):  
S. Douglas Frasier ◽  
Richard Horton ◽  
Robert A. Ulstrom
Keyword(s):  
Plasma Concentration ◽  
Urinary Excretion ◽  
Congenital Adrenal Hyperplasia ◽  
Conversion Ratio ◽  
Metabolic Clearance ◽  
Adrenal Hyperplasia ◽  
Metabolic Clearance Rate ◽  
Hydroxylase Deficiency ◽  
Glucocorticoid Administration

The plasma concentration of androstenedione and testosterone, metabolic clearance rate of androstenedione, and in vivo conversion ratio of androstenedione to testosterone have been studied in a normotensive 5-year-old female with congenital adrenal hyperplasia due to a deficiency of 11 β-hydroxylase. Prior to glucocorticoid administration, the urinary excretion of 17-ketosteroids varied from 2.2 to 4.9 mg/24 hours, urinary excretion of pregnanetriol varied from 0.7 to 2.2 mg/24 hours, and total 17-hydroxysteroid excretion varied from 1.2 to 7.5 mg/24 hours. Urinary tetrahydro-11-deoxy cortisol (TSH) was detected at a concentration of 550 µg/24 hours. The plasma concentration of androstenedione varied from 100 to 530 mµg/100 ml and the plasma concentration of testosterone varied from 40 to 90 mµg/100 ml. These values are significantly elevated when compared to those obtained in normal prepubertal females. Urinary steroid excretion and plasma androgen concentrations fell to normal in response to glucocorticoid administration. The metabolic clearance rate of androstenedione was 890 liters per day per M2 and the in vivo conversion ratio of androstenedione to testosterone was 11%. The calculated production rate of androstenedione was 4.7 mg per day per M2. Virilization in congenital adrenal hyperplasia due to 11 β-hydroxylase deficiency can be explained by an elevated plasma concentration of testosterone, which can be accounted for on the basis of conversion from androstenedione.

Validation of a new method for determination of free fatty acid turnover

1987 ◽  
Vol 252 (3) ◽  
pp. E431-E438 ◽  
Author(s):  
J. M. Miles ◽  
M. G. Ellman ◽  
K. L. McClean ◽  
M. D. Jensen
Keyword(s):  
Steady State ◽  
Fatty Acid ◽  
Free Fatty Acid ◽  
Clearance Rate ◽  
Experimental Period ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
State Equations ◽  
Tracer Methods

The accuracy of tracer methods for estimating free fatty acid (FFA) rate of appearance (Ra), either under steady-state conditions or under non-steady-state conditions, has not been previously investigated. In the present study, endogenous lipolysis (traced with 14C palmitate) was suppressed in six mongrel dogs with a high-carbohydrate meal 10 h before the experiment, together with infusions of glucose, propranolol, and nicotinic acid during the experimental period. Both steady-state and non-steady-state equations were used to determine oleate Ra ([3H]oleate) before, during, and after a stepwise infusion of an oleic acid emulsion. Palmitate Ra did not change during the experiment. Steady-state equations gave the best estimates of oleate inflow approximately 93% of the known oleate infusion rate overall, while errors in tracer estimates of inflow were obtained when non-steady-state equations were used. The metabolic clearance rate of oleate was inversely related to plasma concentration (P less than 0.01). In conclusion, accurate estimates of FFA inflow were obtained when steady-state equations were used, even under conditions of abrupt and recent changes in Ra. Non-steady-state equations, in contrast, may provide erroneous estimates of inflow. The decrease in metabolic clearance rate during exogenous infusion of oleate suggests that FFA transport may follow second-order kinetics.

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.

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