omega 6/omega 3 polyunsaturated fatty acid supplementations in renal cell model lead to a particular regulation through lipidome for preserved omega 6/omega 3 ratios

International audiencePolyunsaturated fatty acids (PUFA) supplementations modify cell lipid composition leading to a change in cell function. However, the effect of PUFA supplementations in renal model cell on the kidney epithelial cells membrane fatty acid profile is not known. Therefore, the purpose of this study was to determine the effects of PUFAs with different omega 6/omega 3 ratios supplementations in the kidney epithelial cells and the type of supplementation that can be used as cellular protection during kidney transplantation. For that, we used as model the LLCPK-1 cell and determined their membrane fatty acid (FA) composition after supplementation with three different commercial food supplements. These supplements consist of S1: docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) with omega 6/omega 3 ratio = 0.1, S2: DHA, EPA, linoleic acid (LA) and gamma-linoleic acid (GLA) with omega 6/omega 3 ratio = 2.5, or S3: alpha-linolenic acid (ALA) and LA with omega 6/omega 3 ratio near 1. Cells were incubated for 24 hr with 30 mu M of omega 3 fatty acids from each supplement. Fatty acid composition of control and experimental groups was analysed by gas chromatography after extraction of lipids and fatty acids methylation. The efficiency of cell PUFA supplementation was achieved by showing 2 to 4 fold increases in cell PUFA incorporation. Whatever the supplementation used, the cell saturated fatty acids (SFA) were decreased by 50% following the three supplementations used (p<0.001) as compared to control group. These decreases in SFA were compensated in part by increasing monounsaturated fatty acid levels. All these changes were observed with constant of cell omega 6/omega 3 ratio whatever the supplementations used. These data suggest that the supplements, with long chain polyunsaturated fatty acids or their precursors, lead to important regulation in the lipidome (desaturases and elongases) associated to preserved omega 6/omega 3 ratios. The fatty acids remodeling may represent an interesting new mechanism by which renal FA homoestasis could occurred

Focal cerebral ischaemia induces a decrease in activity and a shift in ouabain affinity of Na+, K+-ATPase isoforms without modifications in mRNA and protein expression

In a mouse model of focal cerebral ischaemia, we observed after 1 h of ischaemia, that the total Na+, K+-ATPase activity was decreased by 39.4%, and then did not vary significantly up to 6 h post-occlusion. In the sham group, the dose-response curves for ouabain disclosed three inhibitory sites of low (LA), high (HA) and very high (VHA) affinity. In ischaemic animals, we detected the presence of only two inhibitory sites for ouabain. After 1 h of permanent occlusion, the first site exhibited a low affinity while the second site presented an affinity intermediate between those of HA and VHA sites, which evolved after 3 h and 6 h of occlusion towards that of the VHA site. The presence of only two ouabain sites for Na+, K+-ATPase after ischaemia could result from a change in ouabain affinity of both HA and VHA sites (alpha2 and alpha3 isoforms, respectively) to form a unique component. Irrespective of the duration of ischaemia, the smaller activity of this second site accounted entirely for the loss in total activity. Surprisingly, no modifications in protein and mRNA expression of any alpha or beta isoforms of the enzyme were observed, thus suggesting that ischaemia could induce intrinsic modifications of the Na+, K+-ATPase