Elimination of Porcine Secretin in Pigs

1978 ◽  
Vol 54 (1) ◽  
pp. 61-68
Author(s):  
J. Fahrenkrug ◽  
O. B. Schaffalitzky de Muckadell ◽  
J. J. Holst
Keyword(s):  
Whole Blood ◽  
Clearance Rate ◽  
Intravenous Infusion ◽  
Half Life ◽  
Metabolic Clearance ◽  
Distribution Space ◽  
Metabolic Clearance Rate ◽  
The Mean ◽  
Arteriovenous Difference

1. The elimination of immunoreactive secretin was studied in anaesthetized pigs by using constant infusions of pure natural porcine secretin. 2. The mean metabolic clearance rate was 15·4 ml min—1 kg—1, and was independent of the level at which it was determined. The mean distribution space was 64·4 ml/kg. The half-life of secretin after termination of the infusion averaged 2·6 min. 3. During intravenous infusion of secretin in a dose of 27·8 pmol h—1 kg—1 the renal extraction was 52%. Exclusion of the kidneys increased plasma secretin concentration from 26·5 pmol/l to 47·3 pmol/l and increased the half-life to 4·4 min. 4. Exclusion of the liver during infusion of secretin in a dose of 27·8 pmol h—1 kg—1 resulted in an increment in plasma secretin concentration of 7·8 pmol/l and an increase of the half-life to 3·6 min. 5. A gradient of endogenous secretin across the liver was present but no arteriovenous difference was found across the foreleg. 6. Incubation of secretin with whole blood or serum for 20 min at 37°C did not result in any degradation of secretin.

THE METABOLIC CLEARANCE RATE, PRODUCTION RATE AND CONVERSION RATIOS OF OESTRONE IN THE SHEEP

1973 ◽  
Vol 58 (3) ◽  
pp. 435-446 ◽  
Author(s):  
J. R. G. CHALLIS ◽  
F. A. HARRISON ◽  
R. B. HEAP
Keyword(s):  
Steady State ◽  
Whole Blood ◽  
Clearance Rate ◽  
Conversion Ratio ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Transfer Constant ◽  
Pregnant Sheep ◽  
Tracer Kinetic ◽  
The Mean

SUMMARY The metabolic clearance rate of oestrone from whole blood and its conversion to oestradiol-17β and oestradiol-17α were measured in pregnant and non-pregnant sheep using tracer kinetic techniques. The clearance rate of oestrone for all animals (3·435 ± 0·212 (s.e.m.) 1/min) was significantly greater than that of oestradiol-17β (2·449 ± 0·155 1/min). The mean conversion ratio of oestrone to oestradiol-17β was 23·8±1·6%, and that of oestrone to oestradiol-17α was 17·7 ± 2·5%. The transfer constant of oestrone to oestradiol-17β was estimated to be 17·5 ± 1·6% compared with that of oestradiol-17β to oestrone which was 23·2 ± 2·5%. The production of oestrone increased from values of 0·141 and 0·240 μg/min up to 2 days before parturition, to between 0·660 and 1·881 μg/min during the last 24 h of pregnancy; these values were appreciably greater than those of oestradiol-17β. During the continuous infusion of [3H]oestrone or [3H]oestradiol-17β and when a steady state had been reached, the uptake by erythrocytes of [3H]oestrone was 22·3%, that of [3H]oestradiol-17β, 6·6%, and that of [3H]oestradiol-17α, 22·0%. In three experiments on one sheep, the uptake of [3H]oestrone across the head was 11–16%.

THE KINETICS OF OESTRADIOL-17β METABOLISM IN THE SHEEP

1973 ◽  
Vol 57 (1) ◽  
pp. 97-110 ◽  
Author(s):  
J. R. G. CHALLIS ◽  
F. A. HARRISON ◽  
R. B. HEAP
Keyword(s):  
Steady State ◽  
Whole Blood ◽  
Clearance Rate ◽  
Venous Blood ◽  
Conversion Ratio ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Tracer Kinetic ◽  
The Mean ◽  
Kinetics Of

SUMMARY The metabolic clearance rate of oestradiol-17β from whole blood and its conversion to oestrone and oestradiol-17α were measured in pregnant and non-pregnant (cyclic, lactating and anoestrous) sheep using tracer kinetic techniques. The metabolic clearance rate was much the same in sheep in different reproductive states (mean in all animals (±s.e.m.) = 2·449 ± 0·155 1/min). The highest values were reached on days 143–145 of pregnancy (3·287 ± 0·3351/min). The mean conversion ratio of oestradiol-17β to oestrone was 17·0 ± 2·2%, and that of oestradiol-17β to oestradiol-17α was 14·1 ± 1·1%. The production rate of oestradiol-17β increased from 0·007 to 0·103 μg/min up to 3 days before parturition to 0·035–1·257 μg/min during the last 12 h of pregnancy. During the continuous infusion of [3H]oestradiol-17β and when a steady state had been reached, approximately 20–30% of the radioactivity in whole blood could be extracted with ether. Of this radioactivity more than 90% was attributable to labelled oestradiol-17β, oestrone and oestradiol-17α in jugular blood, though only about 70% could be accounted for as these oestrogens in uterine venous blood.

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

Fate of circulating renin in conscious rats

1987 ◽  
Vol 252 (1) ◽  
pp. E136-E146 ◽  
Author(s):  
S. Kim ◽  
H. Iwao ◽  
N. Nakamura ◽  
F. Ikemoto ◽  
K. Yamamoto
Keyword(s):  
Clearance Rate ◽  
Half Life ◽  
High Performance ◽  
Slow Component ◽  
High Performance Liquid Chromatographic ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Conscious Rats ◽  
Liver And Kidney ◽  
Liquid Chromatographic

Highly purified 125I-labeled rat renal renin (125I-renin) was given intravenously to conscious rats to study the fate of circulating renin. Specific antirat renin antiserum was used to identify the labeled renin molecules. In sham-operated rats, the disappearance of 125I-renin from the plasma showed two exponential components with a half-life of 6.7 +/- 0.4 min for the rapid component and 65.1 +/- 5.7 min for the slow component. The metabolic clearance rate was 11.4 +/- 1.0 ml X min-1 X kg-1. In bilaterally nephrectomized rats, the metabolic clearance rate of 125I-renin was reduced by 55%, but the half-life of the slow component remained unchanged. Seventy percent hepatectomy caused a 54% decrement in the metabolic clearance and prolonged the half-life of the slow component. Five minutes after injection of 125I-renin, approximately 59 and 11% of the administered 125I-renin had accumulated in the liver and the kidneys, respectively, and at later time points the 125I-renin was highly concentrated in these organs. High-performance liquid chromatographic analysis of the liver and kidney extracts demonstrated that 125I-renin was catabolized by these organs. Biliary excretion of 125I-renin was negligible. Urinary excretion of 125I-renin up to 120 min was approximately 2% of the injected dose. We conclude that both the liver and the kidney are responsible for the clearance of circulating renin, with participation of the liver being predominant.

The influence of disulfiram on the half life and metabolic clearance rate of diphenylhydantoin and tolbutamide in man

1976 ◽  
Vol 9 (5-6) ◽  
pp. 439-441 ◽  
Author(s):  
T. Lysbo Svendsen ◽  
M. Brandt Kristensen ◽  
J. M�lholm Hansen ◽  
L. Skovsted
Keyword(s):  
Clearance Rate ◽  
Half Life ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate

Physiology of 24,25-dihydroxyvitamin D3 in normal human subjects

1982 ◽  
Vol 243 (5) ◽  
pp. E370-E374 ◽  
Author(s):  
R. Kumar ◽  
R. Wiesner ◽  
M. Scott ◽  
V. L. Go
Keyword(s):  
Production Rate ◽  
Biliary Excretion ◽  
Clearance Rate ◽  
Half Life ◽  
Human Subjects ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Dihydroxyvitamin D3 ◽  
Normal Human ◽  
24,25 Dihydroxyvitamin D3

We determined the metabolic clearance and production rates of 24,25-dihydroxyvitamin D3 in four normal healthy adults. We also examined the excretion of radioactivity in stool, urine, and bile after the intravenous administration of 24,25-[3H]dihydroxyvitamin D3 to human subjects. 24,25-Dihydroxyvitamin D3 is rapidly cleared from the plasma with a half-life of approximately 390 +/- 25 min (mean +/- SE). The metabolic clearance rate of 24,25-dihydroxyvitamin D3 was 9.2 +/- 1.5 liters/day with a production rate of 26.4 +/- 7.2 micrograms/day (mean +/- SE). Within 1 day 13.0 +/- 4.2% (mean +/- SE) of the administered dose had appeared in the stool; by day 7, 48.8 +/- 2.7% of the dose had appeared in the feces. Within 24 hr, 6.4 +/- 0.8% of the administered dose appeared in the urine; 7.4 +/- 1.8% of the dose had appeared in the urine within 2 days. The biliary excretion of 24,25-dihydroxyvitamin D3 was studied in two subjects. By 8 h, 15.3 +/- 1.3% of the administered dose had appeared in the bile. The metabolites present in bile, feces, and urine were much more polar than 24,25-dihydroxyvitamin D3. These results demonstrate that 24,25-dihydroxyvitamin D3 is rapidly cleared from plasma and is excreted in the feces (probably via the bile) and urine of normal human subjects.

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