The modifying effect of manganese on the enzymic profiles and pathways of carbohydrate metabolism in rat liver and adipose tissue during development

1. The binding of trimethyltin and triethyltin to rat liver mitochondria was determined and the results were analysed by the method of Scatchard (1949). 2. One binding site (site 1) has the correct characteristics for the site to which trimethyltin and triethyltin are attached when they inhibit oxidative phosphorylation. For each compound the concentration of site 1 is 0.8nmol/mg of protein and the ratios of their affinity constants are the same as the ratio of the concentrations inhibiting oxidative phosphorylation. 3. Binding site 1 is present in a fraction derived from mitochondria containing only 15% of the original protein. In this preparation ultrasonication rapidly destroyed site 1. 4. Dimethyltin and diethyltin do not prevent binding of triethyltin to rat liver mitochondria, whereas triethyl-lead does. 5. Trimethyltin and triethyltin bind to mitochondria from brown adipose tissue and the results indicate a binding site 1 similar to that in rat liver mitochondria. 6. The advantages and limitations of this approach to the study of inhibitors are discussed.

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Ontogeny of acyl-CoA: cholesterol acyltransferase in rat liver, intestine, and adipose tissue

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1992.262.4.g599 ◽

1992 ◽

Vol 262 (4) ◽

pp. G599-G602

Author(s):

M. T. Little ◽

P. Hahn

Keyword(s):

Adipose Tissue ◽

Rat Liver ◽

Animal Studies ◽

Coenzyme A ◽

Cholesterol Metabolism ◽

Cholesterol Acyltransferase ◽

Dietary Manipulation ◽

Acat Activity ◽

Brown Adipose ◽

Acyl Coenzyme A

The development of acyl-coenzyme A: cholesterol acyltransferase (ACAT), was determined in the rat liver, intestine, and white (WAT) and brown adipose tissue (BAT). Animal studies have shown that dietary manipulation of cholesterol metabolism during an animal's early development can have persistent and permanent effects. Therefore it is important that the ontogeny of ACAT, one of the key enzymes in cholesterol metabolism, be clearly established. White Wistar rats were killed on day 21 of gestation, at birth, and on postnatal days 10, 14, 18, 21, 22, 25, 30, and 60. The tissues were rapidly excised, microsomes were prepared, and the activity of ACAT was measured as the rate of incorporation of [1-14C]oleoyl coenzyme A into cholesterol esters. Age-specific changes were observed in three of the four tissues investigated. Rat liver and intestine possess significant amounts of ACAT activity throughout development with marked variations in activity during this time. ACAT activity in BAT is low and variable throughout development with the exception of high activity noted in the adult animal. WAT contained little or no ACAT activity during development.

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Different effects of sex hormones on rat liver and adipose tissue pseudocholinesterase activity

Pharmacological Research ◽

10.1016/1043-6618(95)86591-8 ◽

1995 ◽

Vol 31 ◽

pp. 83

Author(s):

K. Oresˇković ◽

E. Kunec-Vajić

Keyword(s):

Adipose Tissue ◽

Sex Hormones ◽

Rat Liver

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Specific antibodies and the selective inhibitor ICI 118233 demonstrate that the hormonally stimulated ‘dense-vesicle’ and peripheral-plasma-membrane cyclic AMP phosphodiesterases display distinct tissue distributions in the rat

Biochemical Journal ◽

10.1042/bj2480897 ◽

1987 ◽

Vol 248 (3) ◽

pp. 897-901 ◽

Cited By ~ 21

Author(s):

N J Pyne ◽

N Anderson ◽

B E Lavan ◽

G Milligan ◽

H G Nimmo ◽

...

Keyword(s):

Adipose Tissue ◽

Plasma Membrane ◽

Cyclic Amp ◽

Rat Liver ◽

White Adipose Tissue ◽

Tissue Homogenate ◽

Phosphodiesterase Activity ◽

Cyclic Amp Phosphodiesterase ◽

Peripheral Plasma ◽

Membrane Enzyme

Polyclonal-antibody preparations DV1 and PM1, raised against purified preparations of rat liver insulin-stimulated ‘dense-vesicle’ and peripheral-plasma-membrane cyclic AMP phosphodiesterases, were used to analyse rat liver homogenates by Western-blotting techniques. The antibody DV1 identified only the 63 kDa native subunit of the ‘dense-vesicle’ enzyme, and the antibody PM1 only the 52 kDa subunit of the plasma-membrane enzyme. These antibodies also detected the subunits of these two enzymes in homogenates of kidney, heart and white adipose tissue from rat. Quantitative immunoblotting demonstrated that the amount of these enzymes (by wt.) varied in these different tissues, as did the expression of these two enzymes, relative to each other, by a factor of as much as 7-fold. The ratio of the dense-vesicle enzyme to the peripheral-plasma-membrane enzyme was lowest in liver and kidney and highest in heart and white adipose tissue. ICI 118233 was shown to inhibit selectively the ‘dense-vesicle’ cyclic AMP phosphodiesterase in liver. It did this in a competitive fashion, with a Ki value of 3.5 microM. Inhibition of tissue-homogenate cyclic AMP phosphodiesterase activity by ICI 118233 was used as an index of the contribution to activity by the ‘dense-vesicle’ enzyme. By this method, a tissue distribution of the ‘dense-vesicle’ enzyme was obtained which was similar to that found by using the immunoblotting technique. The differential expression of isoenzymes of cyclic AMP phosphodiesterase activity in various tissues might reflect a functional adaptation, and may provide the basis for the different physiological actions of compounds which act as selective inhibitors.

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