Comparison of somatostatin-28 and somatostatin-14 clearance by the perfused rat liver

1985 ◽  
Vol 63 (1) ◽  
pp. 62-67 ◽  
Author(s):  
M. Seno ◽  
Y. Seino ◽  
Y. Takemura ◽  
S. Nishi ◽  
H. Ishida ◽  
...  
Keyword(s):  
Rat Liver ◽  
Gel Filtration ◽  
Perfused Rat Liver ◽  
Half Time ◽  
Hepatic Extraction Ratio ◽  
Plasma Extract ◽  
Second Peak ◽  
Somatostatin 14

The hepatic clearances of somatostatin (SS)-28 and SS-14 by the perfused rat liver were compared, using a recirculating, plasma-free, erythrocyte-containing perfusion system. The disappearance rate constant, half time, clearance, and hepatic extraction ratio when 1.2 nM SS-28 was added to the perfusate were 0.0221 ± 0.0051 min−1, 36.6 ± 7.6 min, 0.34 ± 0.08 mL/min, and 17.2 ± 3.9%, respectively. The corresponding values obtained when SS-14 was added to the perfusate were 0.0405 ± 0.0022 min−1, 17.3 ± 1.0 min, 0.71 ± 0.05 mL/min, and 35.4 ± 2.6%, respectively. The differences between the SS-28 and SS-14 indices were all statistically significant. In addition, the perfusates with SS-28 added were eluted on Sephadex G-25 fine columns and somatostatinlike immunoreactivity (SLI) was determined. No SS-14 was found in perfusate containing SS-28 at both 5 and 30 min after the beginning of the perfusion. To investigate whether or not the liver plays an important role in the clearance of SS-28 or the conversion of SS-28 to SS-14 in vivo, the plasma disappearance of 2 μg SS-28 was compared in the whole rat and the functionally hepatectomized model. The half time of plasma SS-28 was 1.43 ± 0.12 min in the whole rat, significantly shorter than the 2.20 ± 0.14 min in the hepatectomized model. Gel filtration of plasma extract samples at 0.5 min after the SS-28 injection showed two major peaks of SLI: a first peak corresponding to SS-28 and a second peak coeluted in the position of SS-14 in both the whole rat and the hepatectomized model. At 4 min after the SS-28 injection, the first peak disappeared and only a small second peak was observed. These results suggest that SS-28 is cleared by the rat liver in vivo and in vitro and that it is cleared more slowly than SS-14. Furthermore, we find that little, if any, conversion of SS-28 to SS-14 occurs in the liver.

Bioassay of endotoxin clearance in vivo and by perfused rat liver

1976 ◽  
Vol 231 (1) ◽  
pp. 258-264 ◽  
Author(s):  
BJ Buchanan ◽  
JP Filkins
Keyword(s):  
Linear Relationship ◽  
Rat Liver ◽  
Salt Solution ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Half Time ◽  
Rat Blood ◽  
Endotoxin Concentration ◽  
Induction Of Tolerance

Endotoxin clearances in vivo and by the isolated perfused rat liver were evaluated via bioassay in lead-sensitized rats. A linear relationship between the probit of shock lethality and the endotoxin dose in the probit range of 4-6 was validated. Endotoxin clearance in normal, fed rats displayed a linear relationship between the logarithm of the blood endotoxin concentration and time throughout the period of 15-240 min at doses of 500 and 1,000 mug/ rat; the half-time values were 58-63 min. Decreasing the endotoxin dose to 250 mug resulted in multiphasic clearance curves. Induction of tolerance to endotoxin resulted in marked acceleration of endotoxin clearance. Endotoxin clearance from the isolated perfused rat liver was not influenced by serum or rat blood as compared to clearance from a balanced salt solution. These data suggest that a physiologically stressful dose of endotoxin is slowly cleared from the blood and, therefore, circulates for prolonged periods.

Degradation and conversion of somatostatin in normal and diabetic rats in vivo and in vitro

1988 ◽  
Vol 66 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Michiyo Seno ◽  
Kinsuke Tsuda ◽  
Norikazu Kitano ◽  
Jun Takeda ◽  
Hirofumi Fukumoto ◽  
...  
Keyword(s):  
Jugular Vein ◽  
Hepatic Clearance ◽  
Diabetic Rats ◽  
Gel Chromatography ◽  
Plasma Samples ◽  
Half Time ◽  
And Control ◽  
Somatostatin 14

Plasma somatostatin-like immunoreactivity in the portal and jugular veins of streptozotocin diabetic rats was compared with that in normal control rats. In the diabetic group, somatostatin levels in the portal (p < 0.05) and jugular (p < 0.01) veins were both elevated compared with those in the control group. Moreover, the degree of elevation was greater in the jugular vein than in the portal vein. To further investigate the role of the liver in the clearance of somatostatin-28 in vivo, 2 μg of somatostatin-28 was administered as a bolus into the external jugular vein of intact and functionally hepatectomized rats. The mean half-time of somatostatin-28 was significantly longer in intact diabetic rats than in controls (p < 0.05). The functional hepatectomy did not cause a significant difference in the half-time in diabetic rats but made it longer in control rats. These results suggest that the longer half-time of somatostatin-28 in diabetic rats in vivo is due to its slower hepatic clearance. The hepatic clearance of somatostatin-28 and somatostatin-14 was further studied in vitro using a recirculating liver perfusion method. The hepatic clearance of 1.2 nM of either somatostatin-28 or somatostatin-14 was significantly lower in diabetic rats than in controls (p < 0.01). This indicates that elevated plasma somatostatin levels in diabetic rats are caused at least in part by decreased hepatic clearance of somatostatin. Gel chromatography of plasma samples obtained 0.5 and 4 min after the somatostatin-28 injection into intact, hepatectomized, and nephrectomized rats showed two major peaks: one compatible with somatostatin-28 and the other compatible with somatostatin-14 in elution position, in both diabetic and control rats. When somatostatin-28 was added to perfusate in vitro, however, gel chromatography failed to demonstrate the second peak was compatible with somatostatin-14 even after 30 min of recirculating perfusion. Gel chromatography of plasma samples obtained 5 and 30 min after incubation of somatostatin-28 showed two major peaks: one compatible with somatostatin-28 and the other compatible with somatostatin-14 in both diabetic and control rats. These results suggest that the conversion of somatostatin-28 to somatostatin-14 occurs mainly in plasma in vivo.

scholarly journals Glutathione transferase Zeta catalyses the oxygenation of the carcinogen dichloroacetic acid to glyoxylic acid

1998 ◽  
Vol 331 (2) ◽  
pp. 371-374 ◽  
Author(s):  
Zeen TONG ◽  
Philip G. BOARD ◽  
M. W. ANDERS
Keyword(s):  
Liver Enzyme ◽  
Rat Liver ◽  
Glutathione Transferase ◽  
Gel Filtration ◽  
Rabbit Antiserum ◽  
Glyoxylic Acid ◽  
Dichloroacetic Acid ◽  
Amino Acid Residues

Dichloroacetic acid (DCA), a common drinking-water contaminant, is hepatocarcinogenic in rats and mice, and is a therapeutic agent used clinically in the management of lactic acidosis. DCA is biotransformed to glyoxylic acid by glutathione-dependent cytosolic enzymes in vitro and is metabolized to glyoxylic acid in vivo. The enzymes that catalyse the oxygenation of DCA to glyoxylic acid have not, however, been identified or characterized. In the present investigation, an enzyme that catalyses the glutathione-dependent oxygenation of DCA was purified to homogeneity (587-fold) from rat liver cytosol. SDS/PAGE and HPLC gel-filtration chromatography showed that the purified enzyme had a molecular mass of 27–28 kDa. Sequence analysis showed that the N-terminus of the purified protein was blocked. An internal sequence of 30 amino acid residues was obtained that matched the recently discovered human glutathione transferase Zeta well [Board, Baker, Chelvanayagam and Jermiin (1997) Biochem. J. 328, 929–935]. Western-blot analysis showed that the purified rat-liver enzyme cross-reacted with rabbit antiserum raised against recombinant human glutathione transferase Zeta. The apparent Km and Vmax values of the purified enzyme with DCA as the variable substrate were 71.4 µM and 1334 nmol/min per mg of protein, respectively; the Km for glutathione was 59 µM. Both the purified rat-liver enzyme and the recombinant human enzyme showed high activity with DCA as the substrate. These results demonstrate that the glutathione-dependent oxygenation of DCA to glyoxylic acid is catalysed by a Zeta-class glutathione transferase.

Effects on in vivo and in vitro administration of vinblastine on the perfused rat liver—Identification of crinosomes

1987 ◽  
Vol 47 (3) ◽  
pp. 309-326 ◽  
Author(s):  
J. Ahlberg ◽  
B. Beije ◽  
A. Berkenstam ◽  
Fredrik Henell ◽  
H. Glaumann
Keyword(s):  
Rat Liver ◽  
Perfused Rat Liver

scholarly journals Biogenesis of microsomal membrane glycoproteins in rat liver. II. Purification of soluble glycoproteins and their incorporation into microsomal membranes.

1975 ◽  
Vol 67 (3) ◽  
pp. 700-714 ◽  
Author(s):  
F Autuori ◽  
H Svensson ◽  
G Dallner
Keyword(s):  
Rat Liver ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Exchange Chromatography ◽  
Microsomal Membrane ◽  
Membrane Glycoproteins ◽  
In Vivo Labeling ◽  
Microsomal Membranes

Sialoproteins isolated from the soluble fraction of rat liver could be incorporated into microsomal membranes. This incorporation was dependent on protein concentration, time, and temperature. Sodium dodecyl sulfate gel electrophoresis of membrane proteins after in vitro incorporation showed four major sugar-containing peaks and was similar to that found after in vivo labeling. Most of the incorporated protein was tightly bound to the microsomal membrane. Gel filtration and ion-exchange chromatography revealed the presence of several cytosolic glycoproteins that could be incorporated into microsomes. During prolonged centrifugation in a KBr solution with a density of 1.21 a highly labeled ([3H]glucosamine) protein (mole wt approximately to 70,000) that was actively incorporated into microsomes could be recovered in the upper region of the tube. These results demonstrate that several cytoplasmic glycoproteins of rat liver are transferred into microsomal membranes and that one of these is a lipoprotein.

Purification of the Antihemophilic Factor by Gel Filtration on Agarose

1969 ◽  
Vol 22 (03) ◽  
pp. 577-583 ◽  
Author(s):  
M.M.P Paulssen ◽  
A.C.M.G.B Wouterlood ◽  
H.L.M.A Scheffers
Keyword(s):  
Factor Viii ◽  
Plasma Proteins ◽  
Large Scale ◽  
Gel Filtration ◽  
Large Scale Preparation ◽  
Scale Preparation ◽  
Antihemophilic Factor

SummaryFactor VIII can be isolated from plasma proteins, including fibrinogen by chromatography on agarose. The best results were obtained with Sepharose 6B. Large scale preparation is also possible when cryoprecipitate is separated by chromatography. In most fractions containing factor VIII a turbidity is observed which may be due to the presence of chylomicrons.The purified factor VIII was active in vivo as well as in vitro.

Half-Life of Platelet Factor 4 (PF-4) in Plasma and Platelets from Macaca Mulatta

1977 ◽  
Vol 37 (01) ◽  
pp. 073-080 ◽  
Author(s):  
Knut Gjesdal ◽  
Duncan S. Pepper
Keyword(s):  
Macaca Mulatta ◽  
Half Life ◽  
Human Platelet ◽  
Gel Filtration ◽  
Platelet Factor 4 ◽  
Active Protein ◽  
Platelet Factor ◽  
Membrane Bound

SummaryHuman platelet factor 4 (PF-4) showed a reaction of complete identity with PF-4 from Macaca mulatta when tested against rabbit anti-human-PF-4. Such immunoglobulin was used for quantitative precipitation of in vivo labelled PF-4 in monkey serum. The results suggest that the active protein had an intra-platelet half-life of about 21 hours. In vitro 125I-labelled human PF-4 was injected intravenously into two monkeys and isolated by immuno-precipita-tion from platelet-poor plasma and from platelets disrupted after gel-filtration. Plasma PF-4 was found to have a half-life of 7 to 11 hours. Some of the labelled PF-4 was associated with platelets and this fraction had a rapid initial disappearance rate and a subsequent half-life close to that of plasma PF-4. The results are compatible with the hypothesis that granular PF-4 belongs to a separate compartment, whereas membrane-bound PF-4 and plasma PF-4 may interchange.

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