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F M Ruggiero

Publications and source records attributed to F M Ruggiero.

53 records · Page 3Linked to original sources
PubMed1990

Exchange of free cholesterol between plasma and erythrocytes from hyperthyroid and hypothyroid rats in vitro.

In our previous studies, we found that circulating thyroid hormone levels alter cholesterol partition between plasma and erythrocytes by changing the phospholipid content of erythrocytes (Ruggiero, F. M., et al. (1984) Horm. Metabol. Res. 16, 37-40; Ruggiero, F. M., et al. (1987) Lipids 22, 148-151). As an extension of this work, we now followed the exchange of free cholesterol between plasma and erythrocytes in control, hyperthyroid and hypothyroid rats under various experimental conditions in vitro. In control rats, erythrocytes incubated with plasma at 37 degrees C for 4 hr lose 10% of cholesterol which was esterified by lecithin:cholesterol acyltransferase (LCAT) present in the plasma. In hyperthyroid rats, erythrocytes incubated with plasma lose 30% of cholesterol within the same time. By contrast, in the case of hypothyroid rats incubation for 4 hr was necessary to transfer 24% of free cholesterol from plasma to erythrocytes. Inhibition of cholesterol esterification did not affect the loss of erythrocyte cholesterol in control and in hyperthyroid rats. Ca2+ increased the LCAT activity in the plasma of these rats. The findings shed light on the role of thyroid hormones in regulating cholesterol levels in plasma through active cholesterol transfer between plasma and erythrocytes.

Animals↗
PubMed1989

Decreased activity of the pyruvate translocator and changes in the lipid composition in heart mitochondria from hypothyroid rats.

A study of the transport of pyruvate in heart mitochondria from normal and hypothyroid rats has been carried out. Heart mitochondria from hypothyroid rats translocate pyruvate via the alpha-cyanocinnamate sensitive carrier much more slowly than do mitochondria from normal rats. Kinetic analysis of the pyruvate transport shows that the Vmax of this process is decreased while there is practically no change in the Km values. Neither a decrease in the transmembrane delta pH value nor a decrease in the total number of the pyruvate carrier molecules, titrated with labeled alpha-cyanocinnamate, account for the decreased rate of pyruvate transport. The lower activity of the pyruvate translocator in mitochondria from hypothyroid rats is associated with a parallel decrease of the rate of pyruvate supported oxygen uptake. There is, however, no difference in either the respiratory control ratios or in the ADP/O ratios between these two types of mitochondria. The heart mitochondrial lipid composition is significantly altered in hypothyroid rats. Cardiolipin, particularly, was found to decrease by around 36%. In addition the pattern of fatty acids was found to be altered in mitochondrial membranes from hypothyroid rats. It is suggested that the decreased activity of the pyruvate translocator in heart mitochondria from hypothyroid rats can be ascribed to changes in the lipid environment which surrounds the pyruvate carrier molecule in the mitochondrial membrane.

Animals↗
PubMed1989

Lipid composition of brown adipose tissue mitochondria and microsomes in hyperthyroid rats.

1. The effects of triiodothyronine on the lipid composition of rat brown adipose tissue (BAT) mitochondria and microsomes was investigated by high performance liquid chromatography (HPLC). 2. An increase of about 20% was noted in mitochondrial cholesterol and phospholipids, while a decrease of about 20% for both total cholesterol and phospholipids was observed in microsomes from hyperthyroid rats. 3. The BAT phospholipid composition was altered significantly in mitochondria from T3-treated rats with an increase (41%) of cardiolipin and a decrease (18%) in phosphatidylcholine. 4. In microsomes, a decrease by 25% in phosphatidylinositol was accompanied by a similar additional percentage increase in phosphatidylethanolamine. 5. Important alterations in the fatty acid pattern were found in mitochondrial neutral lipids.

Adipose Tissue, Brown↗
PubMed1988

The effect of doxorubicin on the transport of pyruvate in rat-heart mitochondria.

The effect of doxorubicin on the transport of pyruvate in rat-heart mitochondria was studied. It was found that the rate of pyruvate transport is inhibited by doxorubicin, half maximal inhibition being obtained at concentration of 125 microM of the drug. The inhibition is not due to a change in the transmembrane delta pH nor does it depend on an interaction of doxorubicin with thyol groups of the pyruvate carrier. Doxorubicin also inhibits the pyruvate dependent oxygen uptake and the specific binding of alpha-cyanocinnamate to mitochondria. It is proposed that doxorubicin affects the pyruvate transport by interacting with cardiolipin molecules surrounding the pyruvate carrier in the mitochondrial membrane.

Animals↗
PubMed1988

Effect of hyperthyroidism on the transport of pyruvate in rat-heart mitochondria.

A comparative study of the transport of pyruvate in heart mitochondria from normal and triiodothyronine-treated rats has been carried out. It has been found that the rate of carrier-mediated (alpha-cyanocinnamate-sensitive) pyruvate uptake is significantly enhanced in mitochondria from triiodothyronine-treated rats as compared with mitochondria from control rats. The kinetic parameters of the pyruvate uptake indicate that only the Vmax of this process is enhanced whilst there is no change in the Km value. The enhanced rate of pyruvate uptake is not dependent on the increase of the transmembrane delta pH value (both mitochondria from normal and triiodothyronine-treated rats exhibit the same delta pH value) neither does it depend on the increase of the pyruvate carrier molecules (titration of these last with alpha-cyanocinnamate gives the same total number of binding sites). the pyruvate-dependent oxygen uptake is stimulated by 35-40% in mitochondria from hyperthyroid rats when compared with mitochondria from control rats. There is, however, no difference in either the respiratory control ratios or in the ADP/O ratios between these two types of mitochondria. The heart mitochondrial phospholipid composition is altered significantly in hyperthyroid rats; in particular, negatively charged phospholipid such as cardiolipin and phosphatidylserine were found to increase by more than 50%. Minor alterations were found in the pattern of fatty acids with an increase of 20:4/18:2 ratio. It is suggested that the changes in the kinetic parameters of pyruvate transport in mitochondria from hyperthyroid rats involve hormone-mediated changes in the lipid composition of the mitochondrial membranes which in turn modulate the activity of the pyruvate carrier.

Animals↗
PubMed1987

Effect of hypothyroidism on the lipid composition of rat plasma and erythrocyte membranes.

The effect of hypothyroidism on plasma and erythrocyte membrane lipid components has been investigated. This pathological state is accompanied by a) a cholesterol increase of about 60% in plasma, and at the same time a 22% reduction in erythrocyte membranes; b) 44% and 30% phospholipid level decreases in both plasma and red cell membranes, respectively; and c) almost unaffected phospholipid and fatty acid compositions of both plasma and erythrocyte membranes. All changes were corrected by treatment of the hypothyroid rats with triiodothyronine for two days. These findings suggest that in hypothyroid rats a reduced transfer of cholesterol from plasma to erythrocyte membrane probably takes place. This could explain, at least in part, the increased hematic cholesterol level observed in hypothyroid animals. In red cell membranes, the simultaneous decrease in cholesterol and phospholipid levels does not alter the cholesterol/phospholipid molar ratio, thus avoiding their abnormal function.

Animals↗
PubMed1986

Characterization of the alpha-cyanocinnamate binding site in rat heart mitochondria and in submitochondrial particles.

The effect of pH and substrates on the binding of radiolabelled alpha-cyanocinnamate to mitochondria and submitochondrial particles has been investigated. It has been found that the binding is strongly influenced by the pH of the medium (it decreases on increasing the pH of the medium). The inhibition of pyruvate oxidation by this inhibitor follows the same pH dependence. The pH affects only the affinity of the alpha-cyanocinnamate binding site without changing their total number. A similar pH dependence has been found in inside-out submitochondrial particles where the binding sites are directly accessible. The quantitative parameters of the binding of alpha-cyanocinnamate in submitochondrial particles have been determined. The binding can be prevented or displaced by pyruvate and other substrates of the carrier. The turnover number for pyruvate transport in rat-heart mitochondria has been determined.

Animals↗
PubMed1984

Lipid composition of liver mitochondria and microsomes in hyperthyroid rats.

Triiodothyronine-induced alteration of the lipid pattern in rat-liver mitochondria and microsomes has been investigated. In mitochondria, a 25% total cholesterol decrease and a 14% phospholipid increase have been detected. In these hyperthyroid rat liver organelles, a strong decrease in the total cholesterol/phospholipid molar ratio occurs. On the contrary, in microsomes from the same animals, a decrease of about 23% has been measured for both total cholesterol and phospholipids; hence, in this fraction, the total cholesterol/phospholipid molar ratio is unaffected by hyperthyroidism. The liver mitochondrial phospholipid composition, unlike the microsomal composition, is altered significantly in hyperthyroid rats; a 7.4% phosphatidylcholine decrease is accompanied by a similar additive percentage increase of both phosphatidylethanolamine and cardiolipin. In regard to total phospholipid fatty acid composition in liver microsomes from hyperthyroid rats, no variation has been observed compared with the control rats, whereas in mitochondria from the same animals, a meaningful linoleic acid decrease with a similar arachidonic acid increase has been found. In addition to fatty acid alteration, the separated mitochondrial phospholipid classes also exhibit some increase in stearic acid. Among phospholipids, cardiolipin changes the most of the esterified fatty acids in hyperthyroid rat liver. In this compound, a strong increase in the percentage of both palmitic and stearic acid and a 32.4% decrease of linoleic acid have been found.

Animals↗
PubMed1984

Alteration of plasma and erythrocyte membrane lipid components in hyperthyroid rats.

Cholesterol and phospholipid have been measured in plasma and erythrocyte membrane of hyperthyroid rats. It has been found that while the former is reduced by about 30% in plasma and increased by the same amount in erythrocyte membranes, on the contrary, the latter increases by 35% in both plasma and red cell membranes. It seems that when serum triiodothyronine increases, a major cholesterol transfer occurs from plasma to erythrocyte. In this way, by the concomitant phospholipid increase, it is possible to avoid an alteration of the cholesterol/phospholipid molar ratio in the red cells, thus preventing their abnormal function in hyperthyroid rats. The proposal is made that an additional reason for the plasma cholesterol decrease in hyperthyroid subjects can be attributable to a net transfer of this compound from plasma to erythrocyte.

Animals↗
PubMed1983

Effect of hyperthyroidism on lipogenesis in brown adipose tissue of young rats.

Fatty acid synthetic capacity, investigated both in subcellular fractions and in vivo, is very active in brown adipose tissue of room temperature-acclimated rats. In hyperthyroid animals this tissue, analogously to the liver, exhibits an increased activity of acetyl-CoA carboxylase, fatty acid synthetase and microsomal fatty acid chain elongation, this last mechanism remaining unaffected in mitochondria. An enhancement of reducing capacities of a group of cytoplasmic NADP-dependent enzymes has also been observed in brown adipose tissue of hyperthyroid rats, probably due to a greater use of NADPH in lipogenesis under these conditions. An increase in palmitate oxidation and in polyenoic fatty acids was observed in mitochondria of brown adipose tissue from hyperthyroid animals. The latter increase is related to the importance of these compounds in the regulation of membrane fluidity and probably to an increased resistance to cold in the hyperthyroid state.

Adipose Tissue, Brown↗
PubMed1981

[Comparative study of Lecithin and cephalin exchange between liposomes and mitochondria. Activity measured in the presence and absence of a non-specific carrier protein isolated from rat liver].

Study has been made of the rat liver protein catalyzed exchange of both lecithin and cephalin between liposomes and rat liver mitochondria. It has been shown that the exchange activity of these two phospholipids by the protein is almost the same and is apparently not dependent on the nature of donor liposomes. In contrast the spontaneous exchange activity of the above phospholipids strictly depends on the type of donor liposomes. Moreover, the spontaneous exchange of lecithin at any incubation time appears to be almost 100% higher than that of cephalin.

Animals↗
PubMed1979

[Characteristics of a rat liver cellular extract protein which mediates transport of various phospholipids from liposomes to mitochondria].

The effect of pH, Ca++ and Na+ concentration on the phosphatidylethanolamine transport from liposomes to mitochondria by an aspecific soluble rat liver protein has been studied. Results obtained indicate that at pH higher than 6.5 and Ca++ ion concentrations from 5 mM on the transport is strongly inhibited. Preliminary data with ESR spectrometry concerning the nature of lipoprotein association between phosphatidylethanolamine and carrier protein during the transport are also presented.

Animals↗
PubMedDate not supplied

In vivo effect of acetyl-L-carnitine on succinate oxidation, adenine nucleotide pool and lipid composition of synaptic and non-synaptic mitochondria from cerebral hemispheres of senescent rats.

The effect of acetyl-L-carnitine on succinate oxidation, adenine nucleotide pool and lipid composition of synaptic and 'free', non-synaptic, mitochondria in cerebral hemispheres of senescent rats has been studied. Fisher rats (24- or 28-month-old) were treated with acetyl-L-carnitine (300 mg/kg body wt., intraperitoneally (i.p.)) 3 h before being killed. Oxygen consumption was measured using succinate as a substrate; adenine nucleotides and lipids were analyzed by high performance liquid chromatography (HPLC). Acetyl-L-carnitine reverses, in synaptic mitochondria, the age-related decrease in the respiratory control ratio due to a higher state 4 respiration rate. Administration of acetyl-L-carnitine to senescent rats does not affect the total adenine nucleotide pool of synaptic and non-synaptic mitochondria which was unchanged with age. Finally, pretreatment of senescent rats with acetyl-L-carnitine brings the cholesterol and phospholipid contents of synaptic mitochondria, reduced in senescent rats, to the adult level; pretreatment of adult rats has no such effect. Altogether these results suggest that acetyl-L-carnitine is able to reverse age-related deficits of brain mitochondria.

Journal Article↗
PubMedDate not supplied

Age-dependent decrease in the cytochrome c oxidase activity and changes in phospholipids in rat-heart mitochondria.

The effect of aging on the kinetic characteristics of cytochrome c oxidase in rat heart mitochondria was investigated. Mitochondria from young and aged rats had equivalent Km values for cytochrome c, while the maximal activity of the oxidase was significantly reduced in mitochondria from aged rats. The cytochrome aa3 content was the same in both these two types of mitochondria. The Arrhenius plot characteristics differ for cytochrome oxidase activity in mitochondria from aged rats as compared with young rats in that the breakpoint of the biphasic plot was shifted to a higher temperature. Cardiolipin content was markedly decreased in mitochondrial membrane from aged rats. No alterations were found in the patterns of the phospholipid fatty acid distribution of mitochondrial membranes from young and aged rats. The results support the conclusion that the reduced mitochondrial cytochrome c oxidase activity in aged animals is due to a specific decrease in the cardiolipin content.

Journal Article↗