Effect of magnesium deficiency on delta 6 desaturase activity and fatty acid composition of rat liver microsomes.
Experimental Mg2+ deficiency was induced in a group of rats by feeding them a Mg2+-deficient diet for 23 days. They were pair-fed to compare with a control group of rats fed a Mg2+-sufficient diet. In the Mg2+-deficient group the plasma total cholesterol and triglyceride levels were increased while HDL-cholesterol was decreased. In the Mg2+-deficient group the plasma level of thiobarbituric acid reacting substances (TBARS) used as a measure for lipid peroxidation was increased. The increase was attributed to the increased cytosolic Ca2+ in Mg2+-deficiency which can cause: 1) increase of hydro and endoperoxide levels as a consequence of the increase of arachidonic acid release and eicosanoid synthesis in Mg2+-deficiency, and 2) inhibition of the mitochondrial respiratory activity and activation of Ca2+-dependent proteases which may activate the conversion of xanthine dehydrogenase to xanthine oxidase which generates active O2 species. In the Mg2+-deficient group, the fatty acid composition of the liver microsomes indicated a slower rate of conversion of linoleic acid to arachidonic acid which was consistent with the decrease of delta 6 desaturase activity in liver microsomes of Mg2+-deficient rats as measured in vitro. The decrease of delta 6 desaturase activity was attributed to the lower concentration of actual enzyme molecules as a result of the decreased rate of protein synthesis in Mg2+-deficiency. The possible effects of the increased catecholamine release in Mg2+-deficiency are discussed.
Mahfouz
M M
MM
Burnsides Research Laboratory, University of Illinois, Urbana 61801.
Kummerow
F A
FA
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D003065:Coenzyme A / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D050602:Linoleoyl-CoA Desaturase; D008054:Lipid Peroxides / Q000097:blood; D008274:Magnesium / Q000494:pharmacology; D008275:Magnesium Deficiency / Q000201:enzymology*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D013858:Thiobarbiturates; D014280:Triglycerides / Q000097:blood
D001095:Arachidonic Acids; D008076:Cholesterol, HDL; D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D008054:Lipid Peroxides; D013858:Thiobarbiturates; D014280:Triglycerides; D016718:Arachidonic Acid; D000255:Adenosine Triphosphate; D002784:Cholesterol; D000242:Cyclic AMP; D006903:Hydroxymethylglutaryl CoA Reductases; D044943:Fatty Acid Desaturases; D050602:Linoleoyl-CoA Desaturase; D008274:Magnesium; C029684:thiobarbituric acid; D003065:Coenzyme A