scholarly journals Study of the Physiological Role of 3, 3', 4, 4', 5-Pentachlorobiphenyl Inducible 54 kDa Protein in Cytosol of Rat Liver (Proceedings of the 23rd Symposium on Toxicology and Environmental Health)

Eisei kagaku ◽  
1998 ◽  
Vol 44 (1) ◽  
pp. P19-P19
Author(s):  
Takumi ISHIDA ◽  
Megumu HATSUMURA ◽  
Kenji TASAKI ◽  
Ayako FUKUDA ◽  
Yuko YOSHIOKA ◽  
...  
Keyword(s):  
Environmental Health ◽  
Rat Liver ◽  
Physiological Role

scholarly journals Importance of experimental conditions in evaluating the malonyl-CoA sensitivity of liver carnitine acyltransferase. Studies with fed and starved rats

1981 ◽  
Vol 200 (2) ◽  
pp. 217-223 ◽  
Author(s):  
J D McGarry ◽  
D W Foster
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Rat Liver ◽  
Competitive Inhibition ◽  
Physiological Role ◽  
Rat Liver Mitochondria ◽  
Acid Oxidation ◽  
Carnitine Acyltransferase ◽  
Malonyl Coa

The experiments reconfirm the powerful inhibitory effect of malonyl-CoA on carnitine acyltransferase I and fatty acid oxidation in rat liver mitochondria (Ki 1.5 microM). Sensitivity decreased with starvation (Ki after 18 h starvation 3.0 microM, and after 42 h 5.0 microM). Observations by Cook, Otto & Cornell [Biochem. J. (1980) 192, 955--958] and Ontko & Johns [Biochem. J. (1980) 192, 959--962] have cast doubt on the physiological role of malonyl-CoA in the regulation of hepatic fatty acid oxidation and ketogenesis. The high Ki values obtained in the cited studies are shown to be due to incubation conditions that cause substrate depletion, destruction of malonyl-CoA or generation of excessively high concentrations of unbound acyl-CoA (which offsets the competitive inhibition of malonyl-CoA towards carnitine acyltransferase I). The present results are entirely consistent with the postulated role of malonyl-CoA as the primary regulatory of fatty acid synthesis and oxidation in rat liver.

scholarly journals A STUDY OF THE NUCLEOSIDE TRI- AND DIPHOSPHATE ACTIVITIES OF RAT LIVER MICROSOMES

1962 ◽  
Vol 15 (3) ◽  
pp. 563-578 ◽  
Author(s):  
Lars Ernster ◽  
Lois C. Jones
Keyword(s):  
Rat Liver ◽  
Liver Microsomes ◽  
Physiological Role ◽  
Sodium Deoxycholate ◽  
Inorganic Pyrophosphatase ◽  
Rat Liver Microsomes ◽  
High Concentrations ◽  
Hydrolysis Of ◽  
No Activation

Rat liver microsomes catalyze the hydrolysis of the triphosphates of adenosine, guanosine, uridine, cytidine, and inosine into the corresponding diphosphates and inorganic orthophosphate. The activities are stimulated by Na2S2O4, and inhibited by atebrin, chlorpromazine, sodium azide, and deaminothyroxine. Sodium deoxycholate inhibits the ATPase activity in a progressive manner; the release of orthophosphate from GTP and UTP is stimulated by low, and inhibited by high, concentrations of deoxycholate, and that from CTP and ITP is unaffected by low, and inhibited by high, concentrations of deoxycholate. Subfractionation of microsomes with deoxycholate into ribosomal, membrane, and soluble fractions reveals a concentration of the triphosphatase activity in the membrane fraction. Rat liver microsomes also catalyze the hydrolysis of the diphosphates of the above nucleosides into the corresponding monophosphates and inorganic orthophosphate. Deoxycholate strongly enhances the GDPase, UDPase, and IDPase activities while causing no activation or even inhibition of the ADPase and CDPase activities. The diphosphatase is unaffected by Na2S2O4 and is inhibited by azide and deaminothyroxine but not by atebrin or chlorpromazine. Upon fractionation of the microsomes with deoxycholate, a large part of the GDPase, UDPase, and IDPase activities is recovered in the soluble fraction. Mechanical disruption of the microsomes with an Ultra Turrax Blender both activates and releases the GDPase, UDPase, and IDPase activities, and the former effect occurs more readily than the latter. The GDPase, UDPase, and IDPase activities of the rat liver cell reside almost exclusively in the microsomal fraction, as revealed by comparative assays of the mitochondrial, microsomal, and final supernatant fractions of the homogenate. The microsomes exhibit relatively low nucleoside monophosphatase and inorganic pyrophosphatase activities, and these are unaffected by deoxycholate or mechanical treatment. Different approaches toward the function of the liver microsomal nucleoside tri- and diphosphatases are reported, and the possible physiological role of the two enzymes is discussed.

Thyroid hormone dependent nuclear proteins from rat liver

1982 ◽  
Vol 99 (4) ◽  
pp. 567-572
Author(s):  
Angeles Rodriguez-Pena ◽  
Juan Bernal
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Effective Dose ◽  
Rat Liver ◽  
Physiological Role ◽  
Nuclear Proteins ◽  
Single Administration ◽  
Minimum Effective Dose ◽  
Nuclear Level

Abstract. Two nuclear proteins from rat liver were shown to be dependent on thyroid hormones. These proteins were present in the nucleosol or nucleoplasmic fraction, and were extracted from the nuclei with 0.15 m NaCl at pH8. After thyroidectomy, a 120 000-Mr polypeptide decreased in concentration to levels below 10% of normal control rats and another polypeptide of 81 000-Mr was increased. Treatment with T4 at physiological replacement doses for several days restored the levels of both proteins to normal. A single administration of 50 μg T3 induced a detectable increase of 120K after 14 h, with maximal effects at 48 h after administration. The minimum effective dose of T3 on 120K was 0.5 μg administered for three days. Preliminary observations suggest that the response of 81K to thyroid hormones is much more sensitive than that of 120K. The physiological role of these polypeptides is unknown, but they could be involved in the mode of T3 action at the nuclear level.

scholarly journals Physiological Role of Endogenous Metallothionein in the Immune System(PROCEEDINGS OF 24TH SYMPOSIUM ON TOXICOLOGY AND ENVIRONMENTAL HEALTH)

1999 ◽  
Vol 45 (1) ◽  
pp. P22-22
Author(s):  
Tomoyuki Odani ◽  
Tsuyoshi Nakanishi ◽  
Akiko Matuyama ◽  
Norio Itoh ◽  
Keiichi Tanaka
Keyword(s):  
Immune System ◽  
Environmental Health ◽  
Physiological Role

scholarly journals Physiological Role of Ascorbic Acid Secretion System in the Stomach (Proceedings of the 23rd Symposium on Toxicology and Environmental Health)

Eisei kagaku ◽  
1998 ◽  
Vol 44 (1) ◽  
pp. P2-P2
Author(s):  
Norio MUTO ◽  
Rie EGUCHI ◽  
Yukie AKAGI ◽  
Norio ITOH ◽  
Keiichi TANAKA
Keyword(s):  
Ascorbic Acid ◽  
Acid Secretion ◽  
Environmental Health ◽  
Physiological Role ◽  
Secretion System

The Physiological Role of Fatty Acid Elongation in Particulate Fractions of Rat Liver and Relative Control Factors

1974 ◽  
Vol 2 (6) ◽  
pp. 1215-1218 ◽  
Author(s):  
E. QUAGLIARIELLO ◽  
C. LANDRISCINA
Keyword(s):  
Fatty Acid ◽  
Rat Liver ◽  
Physiological Role ◽  
Fatty Acid Elongation ◽  
Control Factors

Lipoprotein lipase enables triacylglycerol hydrolysis by perfused newborn rat liver

1991 ◽  
Vol 261 (4) ◽  
pp. G641-G647 ◽  
Author(s):  
L. Gimenez-Llort ◽  
J. Vilanova ◽  
N. Skottova ◽  
G. Bengtsson-Olivecrona ◽  
M. Llobera ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Lipoprotein Lipase ◽  
Rat Liver ◽  
Physiological Role ◽  
Water Soluble ◽  
Neonatal Rat ◽  
Endothelial Lipase ◽  
Newborn Rat ◽  
Triacylglycerol Hydrolysis

Fasted 1-day-old rat liver has high heparin-releasable (endothelial) lipoprotein lipase (LPL) activity, and its hepatocytes synthesize LPL protein. To test the physiological role of this LPL, we perfused the isolated organ with a 0.8 mM triacylglycerol (TAG) (Intralipid + glycerol tri[3H]oleate) 6.3% serum medium. Samples of the recirculated perfusate were taken at different times to determine 3H in TAG, free fatty acid (FFA), and water-soluble (WS) fractions. In the medium [3H]TAG disappeared and [3H]FFA and [3H]WS fractions appeared linearly with time. This TAG hydrolysis was 1) absent when medium was recirculated without liver, 2) not affected by chloroquine addition, 3) inhibited by anti-LPL immunoglobulins, 4) absent when serum was omitted from the medium, and 5) restituted when apolipoprotein CII was added to the medium without serum. Therefore, lysosomal lipase is not involved in this TAG hydrolysis, the features of which are characteristic of LPL, not of the so-called "hepatic endothelial lipase." Thus LPL activity enables the neonatal rat liver to hydrolyze and take up circulating TAG, i.e., has the same function as extrahepatic LPL.

scholarly journals A possible physiological role of taurine in the adult female rat liver

1981 ◽  
Vol 21 (4) ◽  
pp. 555-560 ◽  
Author(s):  
Y. PIERRE ◽  
Fernande CHATAGNER
Keyword(s):  
Rat Liver ◽  
Adult Female ◽  
Physiological Role ◽  
Female Rat

scholarly journals The Role of a Rat Liver Cytosolic 54 kDa Protein That is Inducible by Dioxins(PROCEEDINGS OF 24TH SYMPOSIUM ON TOXICOLOGY AND ENVIRONMENTAL HEALTH)

1999 ◽  
Vol 45 (1) ◽  
pp. P19-19
Author(s):  
Takumi Ishida ◽  
Daisuke Maji ◽  
Yuko Yoshioka ◽  
Yuji Ishii ◽  
Kazuta Oguri
Keyword(s):  
Environmental Health ◽  
Rat Liver

Liver glucokinase of the biotin deficient rat

1968 ◽  
Vol 46 (1) ◽  
pp. 75-80 ◽  
Author(s):  
K. Dakshinamurti ◽  
C. Cheah-Tan
Keyword(s):  
Rat Liver ◽  
Specific Activity ◽  
Control Level ◽  
Physiological Role ◽  
Diabetic Animal ◽  
High K ◽  
Rat Livers

The physiological role of liver ATP: D-glucose-6-phosphotransferase with a high Km for glucose is now well recognized. The activity of this enzyme (glucokinase) is greatly reduced in the liver of the starving or diabetic animal. Our results show that glucokinase is reduced by 40–45% in the biotin deficient rat liver. The specific activity of this enzyme decreases during fasting in both control and deficient rat livers. The extent of the increase in glucokinase activity of the deficient rats following refeeding is considerably lower than in control animals. When biotin deficient rats are given either biotin or insulin or both, the liver glucokinase activity is restored to the control level within 24 h.

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