Lipid metabolism in human endothelial cells

Although lipids are largely involved in cardiovascular physiopathology, the lipid metabolism in endothelial cells remains largely unknown. Human umbilical vein endothelial cells (HUVECs) were used to investigate the metabolism of complex lipids. The membrane phospholipid homeostasis results from both de novo synthesis and remodelling that ensures the fine tuning of the phospholipid fatty acid composition. Using [(3)H]-glycerol and phosphoderivatives we showed the efficiency of glycerolipid synthesis from glycerol (0.9 nmol h(-1) mg proteins(-1)), but not from its phosphorylated form suggesting the requirement of a functional glycerol kinase in HUVECs. Conversely, the synthesis of triacylglycerols was very low (less than 5% of phospholipid synthesis). The incorporation rate of fatty acids into phospholipids showed that there is a specific fate for each fatty acid in respect to its chain length and saturation level. Moreover in steady state condition, increasing the long chain omega3 polyunsaturated fatty acids in the medium resulted in an increased polyunsaturated/saturated ratio in phospholipids (from 0.42 to 0.63). [(14)C]O(2) was produced form either [(14)C]-glucose or [(14)C]-palmitate indicating the functionality of the oxidation pathways, although beta-oxidation was less efficient than glucose oxidation. The endothelial cell lipid metabolism involves conventional pathways, with functional rates largely slower than in hepatocytes or in cardiomyocytes.     

Succinate dehydrogenase activity in relation with cardiac morphology in rats fed low erucic acid rapeseed oil

The histopathological status and histologically demonstratable succinate dehydrogenase activity were evaluated on contiguous heart sections of rats fed low erucic acid rapeseed oil for 18 weeks. The histologically demonstratable SDH activity was quantified and could be related with the severity of the lesion at the same location. These results were discussed in terms of effects of dietary fat on mitochondria.     

Dietary n-3 polyunsaturated fatty acids affect the development of renovascular hypertension in rats.

The consequences of a dietary n-3 PUFA supply was investigated on the blood pressure (BP) increase elicited by left renal artery stenosis in rats distributed in 3 groups (n = 8) fed for 8 weeks a semi-purified diet either as control diet or enriched diets (docosahexaenoic acid, DHA, or eicosapentaenoic acid, EPA). The PUFA intake induced large alterations in heart and kidney phospholipid fatty acid profile, but did not influence body weight, cardiac hypertrophy, renal left atrophy and right hypertrophy. Within 4 weeks, BP raised from 120-180 +/- 2 mm Hg in the control group, but only to 165 +/- 3 mm Hg in the n-3 PUFA groups. After stabilization of BP in the 3 groups, the rats received a short administration of increasing dose of perindopril. The lower dose (0.5 mg/kg) moderately decreased BP only in the control group. With higher doses (1, 5 and 10 mg/kg) BP was normalized in the 3 groups, with a higher amplitude of the BP lowering effect in the control group. A moderate n-3 PUFA intake can contribute to prevent the development of peripheral hypertension in rats by a mechanism that may involve angiotensin converting enzyme.     

Primary rat cardiac cell culture: diet of the mother rats as a determinant parameter of cardiomyoblast production from neonates

Two populations of Wistar rats from the same strain were fed two commonly used commercial chows. The yields of myocardial cells for primary culture obtained from neonatal rats in these 2 populations were significantly different. This effect is strickly caused by diet used during pregnancy and is quickly reversible from one pregnancy to the following one in the same females. This diet effect is limited to the yield in cardiomyoblasts and cultures were not found different after 5 days in the same medium.     

Differential protein profiles in interspecific hybrids between Elaeis oleifera and E. guineensis with contrasting responses to somatic embryogenesis competence acquisition

Understanding the molecular events that initiate somatic embryogenesis (SE) may help optimize clonal propagation protocols in oil palm. The objective of this work was to identify differentially abundant proteins during the induction of SE in two interspecific F1 hybrids of Elaeis oleifera?×?Elaeis guineensis with contrasting responses (responsive and non-responsive) to the SE process. Leaf explants were obtained and submitted to SE induction medium for up to 180 days. Explants were collected at 0, 14, 90 and 150 days of induction (doi). Proteins were extracted and analyzed by two-dimensional electrophoresis. Analyses were focused at 14 and 150 doi, representing the initial and late stages of embryogenic competence acquisition, respectively. The results indicate that at 14 doi a high amount of stress is present which results in cellular dedifferentiation. At 90 doi, cells (of the responsive genotype) seem adapted and have kept stress under control, allowing the use of energy for cellular proliferation that occurs at 150 doi. Therefore, the control of stress and oxidation seem to be crucial for callus development. We highlight proteins associated to oxidative stress, protein processing, energy metabolism and development as potentially involved in embryogenic competence acquisition.

     

Effect of change in growth environment on cultured myocardial cells investigated in a standardized medium

Summary Neonatal rat heart cells cultivated in either of two different media which varied only in their serum supplements were transferred to chemically defined medium (Ham's F10) for 24 h before measuring a variety of parameters. The 24-h period of exposure to chemically defined medium was not sufficient to reverse the effects imposed on the cells by the serum used in the first phase of growth. The cells differed in rate and duration of action potentials and contractions. The initial serum composition affected the response of the cells to calcium deficiency. Studies involving the effects of pharmaceutical reagents such as isoproterenol were also influenced by the serum. In attempting to determine the cause and possible mechanism, it was found that mitochondrial membrane permeability for nitroblue tetrazolium (NBT) was unchanged. Although the serum supplements differed in fatty acid composition, the fatty acid profiles of the cell phospholipids were relatively constant. We conclude that (a) the function of the cells is affected by the growth environment, particularly serum; (b) that a short exposure to a uniform chemically defined medium is not sufficient to reverse these effects; and (c) that the differences in effects are not the result of changes in the fatty acid composition of the whole cell phospholipids nor in mitochondrial membrane permeability as measured by NBT.