Impaired myocardial lipid metabolism in phosphate depletion

This study examines the effects of phosphate depletion on myocardial carbohydrate, lipid, and phospholipid metabolism. Rats were studied after 4 (short-term) and 8 to 12 weeks (long-term) of selective dietary phosphate restriction. Myocardial biopsy samples were examined for glucose-6-phosphate and glycogen to evaluate carbohydrate pathways, and for glycerol phosphate and mitochondrial fatty acid oxidation and phospholipid contents to evaluate lipid and phospholipid turnover. The fall in cellular inorganic phosphorus was associated with a fall in myocardial glycogen, glucose-6-phosphate, glycerol phosphate, and cytidine triphosphate, as well as the contents of phosphatidylcholine, phosphatidylethanolamine, and total phospholipid phosphorus. These observations demonstrate impaired phospholipid metabolism, probably at the biosynthetic level. The oxidation of long-chain and short-chain fatty acids is also impaired in phosphate depletion, further demonstrating impaired lipid metabolism. The abnormal phospholipid metabolism may be compatible with the changes in cellular membrane described in phosphate depletion.