Neutral and polar lipid metabolism in liver microsomes of growing rats fed a calcium-deficient diet.
We studied the incorporation of (14)C-labeled fatty acids and glycerol into different classes of glycerolipids in an in vitro system containing liver microsomes from growing Wistar rats fed a calcium-deficient (CaD; 0.5 g/kg) diet for a 60-day period. Desaturase activities and incorporation of the elongation-desaturation metabolites into specific neutral and polar glycerolipids were also studied and correlated with the activities of various enzymes involved in complex lipid metabolism (acyl-CoA synthase, acyl-CoA hydrolase, DAG-acyltransferase, DAG-kinase, lysophospatidate-acyl-CoA transferase, phosphatidate-phosphohydrolase and phospholipase A(2)). Low calcium condition led to a significant increase in the incorporation (relative amounts and specific activities) of both labeled fatty acids and glycerol with a preferential increase of labeling in neutral lipids rather than in phospholipids. Acyl-CoA synthetase, diacylglycerol acyltransferase and diacylglycerol-3-P acyltransferase activities were increased in low calcium microsomes while diacylglycerol kinase, phospholipase A(2) and palmitoyl-, stearoyl-, linoleyl-, alpha-linolenyl, and eicosatrienoyl-desaturases were decreased. The modifications observed in the interlipid and lipid/protein relationships, enzyme activities, and pattern of incorporation of labeled precursors into each glycerolipid class, suggest that decreased intake of calcium should be considered as a harmful risk factor for the development of cardiovascular diseases.
Marra
Carlos A
CA
Instituto de Investigaciones Bioquímicas de La Plata, CONICET-UNLP, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, B1900 BVB, La Plata, Argentina. camarra@atlas.med.unlp.edu.ar
de Alaniz
María J T
MJ
D000818:Animals; D002118:Calcium / Q000172:deficiency*; D004032:Diet; D005227:Fatty Acids / Q000032:analysis / Q000378:metabolism*; D005260:Female; D005990:Glycerol / Q000032:analysis / Q000378:metabolism; D008862:Microsomes, Liver / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D005227:Fatty Acids; D005990:Glycerol; D002118:Calcium