In vitro effect of free bile acids on the bile canaliular membrane phospholipids in the rat

1976 ◽  
Vol 54 (12) ◽  
pp. 1040-1046 ◽  
Author(s):  
I. M. Yousef ◽  
M. M. Fisher
Keyword(s):  
Bile Acid ◽  
Plasma Membranes ◽  
Membrane Phospholipid ◽  
Male Rats ◽  
Membrane Phospholipids ◽  
Experimental Conditions ◽  
Cell Plasma ◽  
Vitro Effect ◽  
Free Bile Acids

Liver cell plasma membranes of male rats were isolated and separated into two fractions, one rich in bile canalicular membranes (BCM) and the other comprising the rest of the plasma membranes (PM). Aliquots of BCM, PM, and microsomes were incubated with deoxycholic, chenodeoxycholic, or cholic acid at bile acid – membrane phospholipid mole ratios up to 100, and the phospholipids solubilized from the membranes were analyzed.Phospholipid solubilization from the PM and from microsomes was linear and apparently nonselective, while that from the BCM was biphasic and distinctly selective. Phosphatidyl choline and phosphatidyl ethanolamine made up 90% of the phospholipids solubilized from the BCM at a bile acid – membrane phospholipid mole ratio sufficient to solubilize about 50% of the total phospholipids of the BCM. Of particular interest was the observation that the molecular species and fatty acid composition of the phospholipids solubilized from the BCM under these experimental conditions were similar to those of bile obtained from the same animal, and were quite unlike those solubilized at higher bile acid – phospholipid mole ratios. The data are discussed in terms of the mechanism of the biliary secretion of phospholipids.

scholarly journals Angiotensin II inhibits NaCl absorption in the rat medullary thick ascending limb

2004 ◽  
Vol 287 (3) ◽  
pp. F404-F410 ◽  
Author(s):  
Nicolas Lerolle ◽  
Soline Bourgeois ◽  
Françoise Leviel ◽  
Gaëtan Lebrun ◽  
Michel Paillard ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Plasma Membranes ◽  
Inhibitory Effect ◽  
Thick Ascending Limb ◽  
Sprague Dawley ◽  
Experimental Conditions ◽  
Nacl Absorption ◽  
Medullary Thick Ascending Limb

NaCl reabsorption in the medullary thick ascending limb of Henle (MTALH) contributes to NaCl balance and is also responsible for the creation of medullary interstitial hypertonicity. Despite the presence of angiotensin II subtype 1 (AT1) receptors in both the luminal and the basolateral plasma membranes of MTALH cells, no information is available on the effect of angiotensin II on NaCl reabsorption in MTALH and, furthermore, on angiotensin II-dependent medullary interstitial osmolality. MTALHs from male Sprague-Dawley rats were isolated and microperfused in vitro; transepithelial net chloride absorption ( JCl) as well as transepithelial voltage ( Vte) were measured. Luminal or peritubular 10−11 and 10−10 M angiotensin II had no effect on JCl or Vte. However, 10−8 M luminal or peritubular angiotensin II reversibly decreased both JCl and Vte. The effect of both luminal and peritubular angiotensin II was prevented by the presence of losartan (10−6 M). By contrast, PD-23319, an AT2-receptor antagonist, did not alter the inhibitory effect of 10−8 M angiotensin II. Finally, no additive effect of luminal and peritubular angiotensin II was observed. We conclude that both luminal and peritubular angiotensin II inhibit NaCl absorption in the MTALH via AT1 receptors. Because of intrarenal angiotensin II synthesis, angiotensin II concentration in medullary tubular and interstitial fluids may be similar in vivo to the concentration that displays an inhibitory effect on NaCl reabsorption under the present experimental conditions.

Effect of streptozotocin-induced diabetes on bile acid sulfation in male rat liver

1984 ◽  
Vol 247 (3) ◽  
pp. G226-G230
Author(s):  
R. B. Kirkpatrick ◽  
B. G. Kraft
Keyword(s):  
Bile Acid ◽  
Specific Activity ◽  
Male Rats ◽  
Male Rat ◽  
Estrogen Metabolism ◽  
Normal Male ◽  
Activity Levels ◽  
Receptor Kinetics ◽  
Streptozotocin Induced Diabetes

The sulfation of bile acids is hormone dependent, being increased in females and ethynylestradiol (EE)-treated males compared with normal males. Diabetes causes significant alterations in estrogen metabolism and uterine estrogen receptor kinetics. Male rats were given streptozotocin (90 mg/kg) and diabetes was verified. An increase in hepatic bile acid sulfotransferase (BAST) activity was significant by 6 days and continued to increase to 29 days. This increase was prevented by insulin replacement. Administration of EE (6.0-600 micrograms X kg-1 X day-1) to normal male rats resulted in a significant increase in hepatic BAST activity; however, administration of similar doses of EE to diabetic males failed to further increase activity levels over the already-elevated levels in the diabetic controls. This increase in in vitro specific activity was accompanied by an increase in the biliary excretion of lithocholate 3-sulfate and taurolithocholate 3-sulfate in 21-day-diabetic animals. Bile flow and total bile acid excretion were also markedly increased in the diabetic animals. The data indicate that streptozotocin-induced diabetes causes a significant increase in hepatic BAST activity. These findings are consistent with an alteration in hepatic estrogen action in streptozotocin-induced diabetes.

scholarly journals A protein antigenically related to nuclear lamin B mediates the association of intermediate filaments with desmosomes.

1990 ◽  
Vol 111 (2) ◽  
pp. 581-588 ◽  
Author(s):  
A Cartaud ◽  
M A Ludosky ◽  
J C Courvalin ◽  
J Cartaud
Keyword(s):  
Intermediate Filaments ◽  
Plasma Membranes ◽  
Polyclonal Antibodies ◽  
Protein S ◽  
Vitro Assay ◽  
Lamin B ◽  
Peripheral Protein ◽  
Cell Biol ◽  
Cell Plasma

Desmosomes are specialized domains of epithelial cell plasma membranes engaged in the anchoring of intermediate filaments (IF). So far, the desmosomal component(s) responsible for this binding has not been unambiguously identified. In the present work, we have examined bovine muzzle epidermis desmosomes for the presence of protein(s) structurally and functionally related to lamin B, the major receptor for IF in the nuclear envelope (Georgatos, S. D., and G. Blobel. 1987. J. Cell Biol. 105:105-115). By using polyclonal antibodies to lamin B in immunoblotting experiments, we find that a desmosomal protein of 140-kD shares epitope(s) with lamin B. Immunoelectron microscopic and urea extraction experiments show that this protein is a peripheral protein localized at the cytoplasmic side of the desmosomes (desmosomal plaques). Furthermore, this protein binds vimentin in an in vitro assay. Since this binding is inhibited by lamin B antibodies, the epitopes common to the 140-kD protein and to lamin B may be responsible for anchoring of intermediate filaments to desmosomes. These data suggest that lamin B-related proteins (see also Cartaud, A., J. C. Courvalin, M. A. Ludosky, and J. Cartaud. 1989. J. Cell Biol. 109:1745-1752) together with lamin B, provide cells with several nucleation sites, which can account for the multiplicity of IF organization in tissues.

BIOSYNTHESIS OF GONADOTROPHINS BY RAT PITUITARIES IN VITRO

1975 ◽  
Vol 66 (3) ◽  
pp. 369-374 ◽  
Author(s):  
MRIDULA CHOWDHURY ◽  
EMIL STEINBERGER
Keyword(s):  
Comparative Study ◽  
Anterior Pituitary ◽  
Male Rats ◽  
Leucine Incorporation ◽  
Experimental Conditions ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Endogenous Proteases ◽  
Pituitary Homogenate

SUMMARY A method has been developed for studying biosynthesis of FSH in the rat pituitary in vitro. Anterior pituitary glands were incubated with [3H]leucine; a specific and sensitive immunoprecipitation technique was used to isolate FSH from the pituitary homogenate. Total FSH content of the samples was measured by a double-antibody radioimmunoassay technique. Using this technique, a comparative study of LH and FSH synthesis in the same pituitary of adult male rats incubated for various intervals (0·5–6 h) was done. Increased incorporation of [3H]leucine into both LH and FSH with time was noted. The rate and amount of [3H]leucine incorporation into FSH was found to be higher than that into LH, indicating that either the rate of FSH synthesis is higher than that of LH or FSH has more leucine residues than LH. Greater susceptibility of LH to degradation by endogenous proteases during dialysis may also reflect less incorporation of [3H]leucine into LH. This method provides a reliable tool for evaluating FSH synthesis under various experimental conditions.

scholarly journals Inactivation of interleukin-6 in vitro by monoblastic U937 cell plasma membranes involves both protease and peptidyl-transferase activities

1993 ◽  
Vol 215 (3) ◽  
pp. 825-831 ◽  
Author(s):  
Amale LAOUAR ◽  
Christian VILLIERS ◽  
Josiane SANCEAU ◽  
Christel MAISON ◽  
Maurice COLOMB ◽  
...  
Keyword(s):  
Interleukin 6 ◽  
Plasma Membranes ◽  
U937 Cell ◽  
Peptidyl Transferase ◽  
Cell Plasma

Effects of hypophysectomy and GH administration on bovine and human GH binding to rat liver membranes

1985 ◽  
Vol 249 (1) ◽  
pp. E56-E62
Author(s):  
J. L. Messina ◽  
S. Eden ◽  
J. L. Kostyo
Keyword(s):  
Binding Sites ◽  
Plasma Membranes ◽  
Specific Binding ◽  
Human Growth ◽  
Male Rats ◽  
Normal Male ◽  
Number Of Binding Sites ◽  
Liver Membranes ◽  
Isolated Liver

Experiments were conducted to investigate the specific binding of highly purified bovine and human growth hormones (bGH and hGH) to purified liver plasma membranes of male rats at various times after hypophysectomy and after the acute intravenous administration of bGH. Liver membranes prepared from hypophysectomized male rats showed a two- to threefold increase in the specific binding of either [125I]iodo-bGH or [125I]iodo-hGH, when compared with membranes prepared from the livers of age-matched normal male rats. The increase in GH binding was apparent within 3 days after hypophysectomy and persisted for a number of weeks after the operation. The increase in GH binding produced by hypophysectomy appeared to be due to an increase in the number of binding sites present on the membranes. The intravenous injection of 200 micrograms of bGH into hypophysectomized male rats 5-60 min before they were killed markedly reduced the ability of liver membranes prepared from these animals to bind [125I]iodo-bGH specifically. This decrease in GH binding seen after the injection of bGH may have been due to the development of a slowly dissociating hormone-binding site complex, which thereby reduced the number of available binding sites. This conclusion is supported by the finding that bGH, which is bound in vitro to isolated liver membranes, dissociates slowly and incompletely in the presence of an excess of unlabeled hormone. Moreover, the degree to which the bound hormone can dissociate appears to depend on the length of time that association is allowed to occur.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro effect of human growth hormone on lymphocyte transformation and lymphocyte growth factors secretion

1989 ◽  
Vol 120 (6) ◽  
pp. 745-752 ◽  
Author(s):  
R. M. Schimpff ◽  
A. M. Repellin
Keyword(s):  
Growth Hormone ◽  
Human Growth Hormone ◽  
Lymphocyte Transformation ◽  
Human Growth ◽  
Experimental Conditions ◽  
Activated Lymphocytes ◽  
Molecular Weights ◽  
Normal Human ◽  
Vitro Effect

Abstract. Cultures of human blood peripheral lymphocytes were performed in the presence or absence of human growth hormone, and also of phytohemagglutinin and normal human serum 10%. After incubation for 48 h, the supernatants were tested for their ability to promote the uptake of [3H]thymidine into lectin-activated lymphocytes. Supernatants from lymphocyte-free control samples, treated in the same manner, were assayed under the same experimental conditions. Variance analysis of the different dose-response relationships was performed. The results of these in vitro experiments confirm that physiological levels of GH inhibit the lectin-induced lymphoproliferation and that lymphocytes secrete an 'activity' able to stimulate the incorporation of [3H]thymidine into lectin activated lymphocytes. Furthermore we show that: 1) Secretion of this lymphocyte-stimulating activity is increased by physiological levels of GH; 2) This lymphocytic secretion is not radioimmunoassayable IGF-I; 3) Using fast protein liquid chromatography (FPLC), this activity appears in fractions with various molecular weights.

Comparative Effects of Vitamin K2 and Vitamin E on Experimental Arteriosclerosis

1999 ◽  
Vol 69 (1) ◽  
pp. 23-26 ◽  
Author(s):  
Seyama ◽  
Hayashi ◽  
Takegami ◽  
Usami
Keyword(s):  
Vitamin E ◽  
Vitamin K ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Male Rats ◽  
Side Chain ◽  
Scavenging Activity ◽  
Experimental Conditions ◽  
Experimental Arteriosclerosis

The comparative effects of vitamin K2 and vitamin E on aortic calcium (Ca) and inorganic phosphorus (P) levels in the aorta and the elastin fraction (fr.) were investigated in male rats after experimental arteriosclerosis was induced by vitamin D2 with atherogenic diet. Both vitamin K2 (100 mg/kg b.w.) and vitamin E (40 mg/kg b.w.) inhibited the increase of Ca and P in the aorta and the elastin fr. from the arteriosclerotic rats. Vitamin K2 (50 mg/kg b.w.) also suppressed the deposition of Ca and P in the aorta, but there was no change due to vitamin K3 or geranylgeraniol (side chain of vitamin K2) administration. Both vitamin K2 and vitamin E showed lipid radical scavenging activity in the in vitro experiment. However, neither vitamin K3 nor geranylgeraniol exhibited anti-arteriosclerotic or radical scavenging activity under the above experimental conditions. It is suggested that vitamin K2 and vitamin E promoted an antiarteriosclerotic effect by radical scavenging activity. These actions of vitamin K2 are required in the structure of 2-methylnaphthoquinone and its side chain (geranylgeraniol).

scholarly journals Iodinated phospholipids and the in vitro iodination of proteins of dog thyroid gland

1977 ◽  
Vol 168 (2) ◽  
pp. 155-160 ◽  
Author(s):  
Joseph L. Rabinowitz ◽  
Carl J. Tavares
Keyword(s):  
Thyroid Gland ◽  
Plasma Membranes ◽  
Fatty Acyl ◽  
Thyroid Cell ◽  
Membrane Phospholipids ◽  
Iodide Uptake ◽  
Thyroid Cells ◽  
Covalently Linked ◽  
A Minor

Slices of dog thyroid gland were incubated with liposomes consisting of 125I-labelled phosphatidylcholine (the iodine was covalently linked to unsaturated fatty acyl chains). The 125I label of 125I-labelled liposomes was incorporated into thyroid protein and/or thyroglobulin at a higher rate than was the 131I label of either Na131I or 131I2. The iodine was shown to be protein-bound by the co-migration of the labelled iodine with protein under conditions where free iodine, iodide and lipid-bound iodine were removed from protein. The uptake of iodine from the iodinated phospholipid was probably due to phospholipid exchange between the iodinated liposomes and the thyroid cell membrane, since (a) 14C-labelled phospholipid was metabolized to 14CO2 and (b) many lipids in the tissue slice became 14C-labelled. A very strong inhibition of iodide ‘uptake’ from Na131I, caused by thiosulphate, produced only a minor inhibition of the incorporation of 125I from 125I-labelled liposomes into thyroid protein and/or thyroglobulin. This implies that free iodide may not necessarily be formed from the iodinated phospholipids before their entrance or utilization in the cell. Synthetic polytyrosine polypeptide suspensions showed some iodination by 131I-labelled liposomes. In tissues with low tyrosine contents, such as liver and kidney, only a trace uptake was observed. Salivary gland showed some uptake. Endoplasmic reticulum of thyroid gland showed a higher iodine uptake than that of the corresponding plasma membranes. These experiments, together with the demonstration of the diet-dependent presence of iodinated phospholipids in dog thyroid, leads us to suggest that iodination of the membrane phospholipids of thyroid cells may be directly or indirectly involved at some stage in the synthesis of thyroglobulin, or exists as a scavenger mechanism, to re-utilize and/or recover released iodine from unstable compounds inside the thyroid cell.

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