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Biomedical subjects

M Zendzian-Piotrowska

Publications and source records attributed to M Zendzian-Piotrowska.

16 recordsLinked to original sources
PubMed2004

Effect of streptozotocin-diabetes on the functioning of the sphingomyelin-signalling pathway in skeletal muscles of the rat.

AIMS/HYPOTHESIS: Ceramide is the main second messenger in the sphingomyelin-transmembrane signalling pathway. The compound is likely to play a role in the induction of insulin resistance. The aim of the present study was to examine the effect of streptozotocin diabetes on the content and composition of ceramides and sphingomyelins and the activity of neutral Mg (2+)-dependent sphingomyelinase and acid sphingomyelinase in different types of skeletal muscle of the rat. METHODS: The experiments were carried out on two groups of male Wistar rats weighing 250-280 g: controls and those treated with streptozotocin at a dose of 60 mg/kg. Determinations were performed on three types of skeletal muscle: the slow-twitch oxidative (soleus), fast-twitch oxidative-glycolytic (red section of the gastrocnemius) and fast-twitch glycolytic (white section of the same muscle). The content and composition of ceramide- and sphingomyelin-fatty acids were determined using gas-liquid chromatography. The activity of the enzymes was measured using N-[(14)CH (3)]-sphingomyelin as the substrate. RESULTS: Twelve different ceramides and sphingomyelins were identified and quantified in each muscle with regard to the fatty acid residue. The ratio of total content of ceramide-saturated fatty acids to the total content of ceramide-unsaturated fatty acids was more than two. In the case of sphingomyelin, the ratio was similar to ceramide in the soleus and much higher in both sections of the gastrocnemius. Treatment with streptozotocin increased the total content of ceramide-fatty acids by 78% (p < 0.001) in the soleus, 27.5% (p < 0.01) in the red and 36.9% (p < 0.001) in the white section of the gastrocnemius. Concomitantly, the total content of sphingomyelin-fatty acids decreased by 43.8%, 31.2%, 24.8% (p < 0.001 in each case) in the respective muscles. The activity of neutral Mg (2+)-dependent sphingomyelinase was elevated by 69.5%, 105.9% and 62.3% in the soleus and red and white gastrocnemius, respectively (p < 0.001 for each muscle). The activity of acid sphingomyelinase was stable in the soleus and white gastrocnemius and decreased by 15.7% (p < 0.01) in the red gastrocnemius. CONCLUSION/INTERPRETATION: The results obtained show that insulin deficiency results in elevation in the content of ceramide in skeletal muscles. This indicates that the hormone is involved in regulation of the activity of the sphingomyelin-signalling pathway in the muscles.

Animals↗
PubMed2004

Effect of endurance training on the sphingomyelin-signalling pathway activity in the skeletal muscles of the rat.

The sphingomyelin signalling pathway has been shown to function in different skeletal muscle types. The aim of the present study was to examine the effect of endurance training on the functioning of the pathway in the muscles. The experiments were carried out on two groups of male Wistar rats: sedentary and trained for six weeks. 24h after cessation of the training rats were anaesthetized and samples of the soleus, red and white section of the gastrocnemius were taken. The content and composition of sphingomyelin-fatty acids and ceramide - fatty acids was determined by means of gas-liquid chromatography. The content of sphingosine and sphinganine was determined by means of high-pressure liquid chromatography. The activity of neutral Mg(++)-dependent sphingomyelinase was determined spectophotometrically using trinitrophenylaminolauroyl-sphingomyelin as the substrate. It has been found that training reduces the total content of sphingomyelin- and ceramide-fatty acids, increases the content of sphinganine and does not affect the content of sphingosine in individual muscle types. The activity of the enzyme in the muscles is also elevated. It is concluded that training affects functioning of the sphingomyelin -signalling pathway in skeletal muscles. The reduction in the content of ceramide may contribute to elevation in glucose uptake in skeletal muscles observed after training.

Animals↗
PubMed2000

Effect of sex and bezafibrate on incorporation of blood borne palmitate into lipids of rat liver nuclei.

The aim of the present study was to investigate whether lipid metabolism in the nuclei is affected by changes in the metabolism of free fatty acids in the liver. The experiments were carried out on 3 groups of rats: 1 - control-male, 2 - female, and 3 - male, treated with bezafibrate (a peroxisome proliferator). The rats received 14C-palmitic acid intravenously. Thirty min later liver samples and blood from the abdominal aorta were taken. The liver nuclei were isolated in sucrose gradient. Lipids were extracted from the nuclei and the liver homogenate and subsequently separated into the following fractions: phospholipids, mono, di- and triacylglycerols, free fatty acids, cholesterol and cholesterol esters. The radioactivity of each fraction was counted. Furthermore, the content of free fatty acids and the fatty acid binding proteins was measured. It was found that radioactivity was present in each lipid fraction obtained from the liver homogenate and from the nuclei. In the female group, the total radioactivity of lipids in the liver homogenate was lower, whereas in the nuclei it was higher in comparison to the male group. The reduction in the radioactivity in the liver was mostly accounted for by decreased radioactivity in the fraction oftriacylglycerols and phospholipids. In the nuclei, the radioactivity of the fraction of phospholipids, free fatty acids and diacylglycerols was elevated. Bezafibrate did not affect the total radioactivity of lipids in the liver and reduced it in the nuclei. In the liver, the drug increased radioactivity mostly in the fraction of phospholipids and reduced it mainly in the fraction of triacylglycerols. In the nuclei, the radioactivity of each lipid fraction examined was reduced. The content of the fraction of free fatty acids in the liver and in the nuclei in the female and in the bezafibrate-treated groups did not differ from the respective value in the control group. The content of fatty acid binding proteins in the nuclei of the female and bezafibrate-treated groups increased in parallel to the elevation in their content in the cytosol. It is concluded that the female sex hormones and bezafibrate influence the transport of selected lipids into the nuclei. The effects seem to be a consequence of the action of these factors directly on the nucleus.

Active Transport, Cell Nucleus↗
PubMed2000

Diabetes affects phospholipid content in the nuclei of the rat liver.

The aim of the present study was to examine the effect of acute streptozotocin diabetes on the content of different phospholipids and the incorporation of blood-borne 14C-palmitic acid into the phospholipid moieties in the rat liver nuclei. Diabetes was produced by intravenous administration of streptozotocin, and determinations were carried out two and seven days thereafter. Phospholipids were extracted from isolated nuclei and separated into the following fractions: sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine and cardiolipin. Following that, they were quantified and radioactivity was measured. It was found that, in comparison to non-diabetic controls, two-day diabetes reduced the total content of phospholipids in the nuclei by 9.6%. The content of phospholipids in the nuclei by 9.6%. The content of phosphatidylcholine and phosphatidylserine was reduced and the content of the remaining phospholipids was stable. The specific activity of phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and cardiolipin, based on radioactivity incorporated from 14C-palmitic acid, was elevated. Seven-day diabetes resulted in a reduction of the total phospholipid content in the nuclei by 39.4%. This was accounted for by a reduction in the content of each phospholipid fraction with the exception of cardiolipin. The specific activity of each phospholipid fraction, was elevated in this group. It is concluded that insulin is involved in the regulation of the nuclear phospholipid content.

Animals↗
PubMed2000

Effect of triiodothyronine on phospholipid metabolism in skeletal muscles of the rat.

The aim of the present study was to examine the effect of treatment with triiodothyronine (T3) on certain aspects of phospholipid metabolism in skeletal muscles. Rats were injected with triiodothyronine (T3) daily (10 microg x 100 g(-1) b.w., s.c.) for six days. Saline-treated rats served as controls. 24 h after the last dose of T3, 14C palmitic acid suspended in the serum of a donor rat, was administered intravenously. Thirty min later, samples of the soleus, white and red section of the gastrocnemius and blood from the abdominal aorta were taken. The muscle phospholipids were extracted and separated into different fractions by means of thin layer chromatography. The following fractions were obtained: shingomeylin, phosphatidylcholine phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine and cardiolipin. The phospholipids were quantified and their radioactivity was measured. The plasma free fatty acid concentration and radioactivity was also determined. Treatment with T3 reduced the content of phosphatidylinositol and phosphatidylserine in each muscle type, whereas the concentration of other phospholipids remained stable. T3 increased markedly incorporation of the blood-borne fatty acids into each phospholipid fraction in the muscles. It is concluded that an excess of T3 influences the metabolism of phospholipids in skeletal muscles.

Animals↗
PubMed2000

Effect of triiodothyronine on the content of phospholipids in the rat liver nuclei.

The aim of the present study was to examine the effect of triiodothyronine (T3) on the content of phospholipids and on the incorporation of blood-borne palmitic acid into the phospholipid moieties in the nuclei of the rat liver. T3 was administered daily for 7 days, 10 microg x 100 g(-1). The control rats were treated with saline. Each rat received 14C-palmitic acid, intravenously suspended in serum. 30 min after administration of the label, samples of the liver were taken. The nuclei were isolated in sucrose gradient. Phospholipids were extracted from the nuclei fraction and from the liver homogenate. They were separated into the following fractions: sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine and cardiolipin. The content and radioactivity of each fraction was measured. It was found that treatment with T3 reduced the content of phosphatidylinositol and increased the content of cardiolipin in the nuclear fraction. In the liver homogenate, the content of phosphatidylinositol decreased and the content of phosphatidylethanolamine and cardiolipin increased after treatment with T3. The total content of phospholipids after treatment with T3 remained unchanged, both in the nuclear fraction and in the liver homogenate. T3 reduced the specific activity of phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and cardiolipin and had no effect on the specific activity of sphingomyelin and phosphatidylinositol both in the fraction of the nuclei and the liver homogenate. It is concluded that excess of triiodothyronine affects the content of phospholipids in the nuclei. The changes in the content of phospholipids in the nuclei largely reflect changes in their content in the liver.

Animals↗
PubMed1999

Effect of endurance training on the phospholipid content of skeletal muscles in the rat.

Only few data are available on the effect of training on phospholipid metabolism in skeletal muscles. The aim of the present study was to examine the effect of 6 weeks of endurance training on the content of particular phospholipid fractions and on the incorporation of blood-borne [14C]-palmitic acid into the phospholipids in different skeletal muscles (white and red sections of the gastrocnemius, the soleus and the diaphragm) of the rat. Lipids were extracted from the muscles and separated using thin-layer chromatography into the following fractions: sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, cardiolipin and neutral lipids (this fraction being composed mostly of triacylglycerols). It was found that training did not affect the content of any phospholipid fraction in soleus muscle. It increased the content of sphingomyelin in white gastrocnemius muscle, cardiolipin and phosphatidylethanolamine in red gastrocnemius muscle and phosphatidylinositol in white gastrocnemius muscle and diaphragm. The total phospholipid content in red gastrocnemius muscle of the trained group was higher than in the control group. Training reduced the specific activity of sphingomyelin and cardiolipin in all muscles, phosphatidylcholine in soleus, red, and white gastrocnemius muscles, phosphatidylserine in all muscles, phosphatidylinositol in all except the soleus muscle, and phosphatidylethanolamine in hindleg muscles, but not in the diaphragm compared to the corresponding values in the sedentary group. It was concluded that endurance training affects skeletal muscle phospholipid content and the rate of incorporation of the blood-borne [14C]palmitic acid into the phospholipid moieties.

Animals↗
PubMed1999

Effect of acute streptozotocin diabetes on fatty acid content and composition in different lipid fractions of rat skeletal muscle.

The aim of the present study was to examine the effect of acute streptozotocin diabetes on long chain fatty acid content and composition in different lipid classes of particular muscle types in the rat. Two days after streptozotocin administration, rats were anesthetised, and the white and red sections of the gastrocnemius, the soleus and the blood were taken. Lipids were extracted with chloroform/methanol and separated into different fractions (phospholipids, free fatty acids, di- and triacylglycerols) by means of thin layer chromatography. Fatty acids of each fraction were identified and quantified by means of gas-liquid chromatography. The diabetes resulted in elevation of the concentration of blood glucose (over four-fold) and the plasma free fatty acid (over two-fold). Total free fatty acid content in the muscles of diabetic rats increased by 26% in the white, 24% in the red gastrocnemius and 21% in the soleus. There were also changes in the composition of that fraction in each muscle. Diacylglycerol fatty acid content was elevated in both parts of the gastrocnemius (the white part by 15%, the red part by 44%) and remained stable in the soleus of the diabetic rats. The content of triacylglycerol fatty acids was elevated only in the red gastrocnemius in the diabetic group (by 112%), but changes in fatty acid composition in this fraction occurred in each muscle. The content of phospholipid fatty acids was elevated in the white gastrocnemius (by 13%) and remained stable in other muscles. There were only minor changes in phospholipid fatty acid composition in the diabetic rats. We concluded that acute insulin deficiency changes fatty acid content and composition in skeletal muscle lipids. The changes depend both on lipid fraction and muscle type.

Animals↗
PubMed1997

Effect of increased uptake of plasma fatty acids by the liver on lipid metabolism in the hepatocellular nuclei.

The nucleus contains different lipids. The aim of the present study was to examine whether increased uptake of free fatty acids by the liver affects lipid metabolism in the hepatocellular nuclei. The experiments were carried out on three groups of Wistar rats: I - male, control; II - male, heparin-treated, and III - female. [14C]-palmitic acid suspended in rat donor serum was administered intravenously 5 and 30 min before tissue samples were taken. Lipids were extracted from isolated liver nuclei and separated into different fractions (phospholipids - PH, monoacylglycerols - MG, diacylglycerols - DG, cholesterol - CH, free fatty acids - FFA, triacylglycerols - TG and cholesterol esters - CHE). It was found that 5 min after administration of the label all isolated nuclear lipid fractions were radioactive. Most of the radioactivity was located in the fraction of PH, TG and FFA. Elevation in the plasma FFA concentration (heparin-treated group) resulted in increased incorporation of [14C]-palmitic acid into the nuclear lipids and changes in its distribution. In the female rats the radioactivity of nuclear lipids was higher than in the male-controls. There were also differences in the percentage distribution of the radioactivity in different lipid fractions between the two groups. The concentration of PH and TG in the nuclei increased only in the heparin-treated but not in the female rats. However, specific activity of the nuclear PH and TG increased in with both groups compared to the male-control group. It is concluded that (a) the blood-borne FFA rapidly enter the nuclear lipid pool and (b) increased uptake of the plasma-borne FFA by the liver affects the nuclear lipid metabolism.

Animals↗
PubMed1996

The plasma borne free fatty acids rapidly enter the hepatocellular nuclei.

Long-chain free fatty acids (FA) were shown to exert a regulatory function in the nucleus. However, the route of their entry remains uncertain. The aim of the present study was to examine whether the extracellular FA enter the hepatocellular nuclei. The experiments were carried out in vivo and in vitro. Intravenous administration of albumin-bound [14C]-palmitic and [14C]-linoleic acid resulted in rapid accumulation of the labels in the nuclear lipids. Unesterified [14C]-palmitic acid represented 22.4 +/- 1.7 and [14C]-linoleic acid 17.6 +/- 1.3 percent of the total lipid radioactivity. In vitro, confocal laser scanning microscopy was used to examine 12-NBD-stearate (a fluorescent derivative of stearate) translocation into the nuclei of isolated hepatocytes. It was found that 12-NBD stearate enters the nucleus and that this uptake depends on the extracellular and/or cytoplasmic concentration. It is concluded that factors (e.g. dietary) leading to alterations in the plasma FA composition and content can result in rapid changes of the nuclear FA pool and thus regulate certain nuclear processes.

4-Chloro-7-nitrobenzofurazan↗
PubMed1994

[Fatty acid binding protein (FABP)].

Although FABPs have been extensively investigated, their function is not finally established. Based upon their tissue expression, binding affinities, regulation, in vitro effects on fatty acid transfer and upon enzymes, it has been postulated that these proteins play an important role in the transport and metabolism of long-chain fatty acid.

Animals↗
PubMed1993

Metabolic adaptation to daily exercise of moderate intensity to exhaustion in the rat.

The rats were made to run daily to exhaustion, for 28 days at a speed of 1,200 m.h-1 on a treadmill set at a gradient of +10 degrees. The training increased the time of running to exhaustion [184 (SD 49) and 308 (SD 28) min on the 1st and 28th day, respectively; P < 0.001]. The body mass was reduced by training [257 (SD 21) g before and 221 (SD 20) g after; P < 0.001] whereas the food intake increased [9 (SD 1) g.100 g-1 body mass before and 14 (SD 2) g after; P < 0.001]. The heart mass was not affected by training. Training increased the resting glycogen concentration in muscles composed of different fibre types (soleus, white and red vastus muscles) and in the liver, but had no effect on its concentration in the heart and diaphragm. During exercise lasting for 30 min glycogen mobilization in the red vastus and soleus muscles and the liver was more pronounced after than before training. A "sparing" effect of training on the skeletal muscles and liver glycogen was markedly apparent only after exercise to exhaustion. The trained rats, contrary to the untrained, did not develop hypoglycaemia during exercise to exhaustion. An increase in the plasma free fatty acid concentration during exercise after training was delayed and attenuated compared to that before training. The 24-h excretion of urea after exercise to exhaustion on the 28th day of training was higher than on the 1st day by 39% (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1990

Effect of hyperglycaemia on muscle glycogen mobilization during muscle contractions in the rat.

In the rat, muscle glycogen is mobilized during the first stage of exercise, despite normoglycaemia. The aim of the present study was to examine if this process could be prevented or reduced by hyperglycaemia. Three experiments were carried out: in the first, rats were forced to run on a treadmill; in the second the gastrocnemius muscle group was made to contract by stimulation of the sciatic nerve and in the third adrenaline was administered subcutaneously. Each group was divided into two subgroups: control and enriched with glucose (hyperglycaemic). It was shown that hyperglycaemia has no effect on running-induced glycogen mobilization in hind-limb muscles of different fibre composition but prevented it totally in diaphragm muscle. Hyperglycaemia also did not affect the glycogen mobilization induced by stimulation of the sciatic nerve. However, it delayed and reduced markedly the glycogenolytic effect of adrenaline. It is concluded that increased glycogenolysis in muscles at the beginning of exercise may be a consequence of a delay in the activation of glucose transporting mechanisms in muscle cells.

Animals↗