Fatty Acid Profiles of Rat Renal Phospholipids during Development

During maturation, rat renal papillary microsomes suffer a rearrangement in their fatty acid phospholipid composition. The most significant changes in total phospholipids are the increase in their content of the 20:4 and a decrease in the levels of 14:0, 16:0, 18:1, 22:6 and 20:3 fatty acids. The changes in total phospholipid fatty acid content are a reflection of the variations in the individual phospholipid composition. During this period, microsomal cholesterol, phospholipid, and protein concentrations present no variations. Steady state fluorescence anisotropy obtained by using TMA-DPH (see text) as a fluorescence probe denoted higher values for 70- versus 10-day-old microsomes. Using DPH as a probe, steady state fluorescence anisotropy was determined in whole microsomes, as well as in total lipid and phospholipid vesicles, from both 10- and 70-day-old papillary cells. No differences were detected in phospholipid and total lipid vesicles between days 10 and 70. On the other hand, 10-day-old microsomes appeared to be less fluid than adult microsomes. The results indicate that these structural changes in kidney membranes during development might affect protein-lipid interaction and, therefore, the activity of many membrane enzymes.

Section: Resultssupporting

confidence: 93%

Section: Fatty Acid Determinationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Changes in Rat Papilla Microsomal Membrane Fluidity during Development

D’Antuono¹,

Sterin-Speziale²

1999

“…The aim of the present report was to find an enzymatic basis that could explain the changes in arachidonate homeostasis and metabolism that occur during kidney maturation [2,4,13]. We had previously demonstrated that in newborn rats renal membrane phospholipids are almost depleted of arachidonic acid [4], show high avidity for exogenous arachidonic acid [2], and low prostaglandin synthesis [13]; while kidney maturation seemed to be characterized by enrichment in membrane arachidonic acid [4] and increase in prostaglandin synthesis [13].…”

Section: Discussionmentioning

confidence: 91%

“…On the other hand, arachidonic acid presented variations in its incorporation, with the highest values occurring during the neonatal period, denoting changes in the deacylationreacylation cycle with age [2]. In a recent study of the fatty acid profile of kidney membrane phospholipids during maturation, we have found a great increase in arachidonic acid content in both papilla and medulla [4]. Apparently, the differing capacity for incorporation of this fatty acid with age plays an important role in membrane maturation.…”

Section: Introductionmentioning

confidence: 76%

Changes in the Kinetic Properties of Renal Arachidonoyl-CoA Synthetase during Development in the Rat

D’Antuono¹,

Kahane²,

Sterín-Speziale³

1998

Self Cite

Changes in endogenous levels of phospholipid arachidonic acid and in its radioactive incorporation can be detected in the rat kidney medulla during maturation. In an effort to explain this phenomenon, the arachidonoyl-CoA synthetase activity in the neonatal (10 days of age) and adult kidney (70-day-old rats) were studied. The neonatal kidney enzyme showed greater affinity, but less capacity than the adult enzyme to incorporate arachidonic acid into the membrane. The apparent K_m values were 27.8 and 73.9 µM while the v_max was 3.68 and 15.7 nmol/min/mg protein, for 10 and 70 days of age, respectively. Affinity for ATP was found to be almost 7-fold greater in adults when compared to neonates. The v_max for ATP also increased during development, with values of 1.04 and 2.87 at 10 and 70 days of age, respectively. Affinity for coenzyme A did not vary between the two stages studied, though the v_max increased 10-fold from 10 to 70 days of age. Since arachidonic acid availability is low in the perinatal stage because of its restricted endogenous synthesis, the higher enzyme affinity for this fatty acid at 10 days of age described here, could be of great importance in helping to capture the low but indispensable amount of arachidonic acid present in maternal milk during lactation.

Differential Branching of the Sphingolipid Metabolic Pathways with the Stage of Development

Facchinetti

Beuret²,

Márquez³

et al. 2003

We have studied sphingomyelin metabolism in the papillae of neonatal (10-day-old) and adult (70-day-old) kidneys of male Wistar rats because sphingolipid second messengers generated by sphingomyelin metabolism are involved in cellular processes such as proliferation, differentiation and apoptosis. We showed that sphingomyelin and ceramide concentrations in homogenized rat papilla tissue increase with the time whereas sphingosine-1-phosphate content decreases. This is consistent with the finding of a higher biosynthesis of the latter sphingolipid in neonatal than in adult rat papillae. De novo synthetized ceramide was, however, higher in adult than in neonatal papilla homogenates probably accounting for the high ceramide content of the adult rat papilla. These results suggest an active de novo pathway not ending in sphingomyelin but instead arresting at ceramide in adult rat papilla tissue, partially metabolized into sphingosine-1-phosphate in neonatal rat papillae. The activity and the expression of sphingosine kinase, one of the enzymes involved in ceramide metabolism, was found to be higher in neonatal than adult rat kidney tissue. The intracellular distribution of sphingosine kinase was also different; in neonatal rat tissue the enzyme was predominantly associated with plasma membranes but it was cytosolic in adult rat papilla tissue. These findings seem to indicate that, in rat renal papillae, the developmental regulation of sphingosine kinase expression and activity addresses the sphingolipid metabolism to the formation of the proliferative metabolite sphingosine-1-phosphate in the neonatal period, and ceramide, which is associated with cell arrest and differentiation in the adult tissue. These data are consistent with the proliferative state necessary for tubular elongation during the neonatal period and the maintenance of the differentiated state in the adult tissue.