Laboratory Investigation

Kidney International (1984) 26, 18–23; doi:10.1038/ki.1984.128

Impaired myocardial lipid metabolism in phosphate depletion

Nachman Brautbar1, Jose Tabernero-Romo1, John C Coats1 and Shaul G Massry1

1Division of Nephrology, Department of Medicine, University of Southern California School of Medicine, Los Angeles, California

Correspondence: Dr N Brautbar, Division of Nephrology, Department of Medicine, University of Southern California School of Medicine, 2025 Zonal Avenue, Los Angeles, California 90033, USA

Received 30 March 1983; Revised 7 November 1983.

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Abstract

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.

Altération du métabolisme lipidique myocardique lors d'une déplétion phosphatée. Cette étude examine les effets d'une déplétion phosphatée sur le métabolisme myocardique des hydrates de carbone, des lipides et des phospholipides. Des rats ont été étudiés après une réduction phosphatée alimentaire sélective de 4 (court terme) et de 8 à 12 (long terme) semaines. Des biopsies myocardiques ont été étudiées pour leur contenu en glucose-6-phosphate et en glycogène afin d'évaluer les voies métaboliques des hydrates de carbone et pour leur importance en glycérol-phosphate, en oxydation mitochondirale des acides gras et en phospholipides pour évaluer le renouvellement lipidique et phospholipidique. La chute du phosphore inorganique cellulaire était associée à une baisse du glycogène, du glucose, du glucose-6-phosphate, du glycérol-phosphate et de la cytidine-triphosphate myocardiques, ainsi qu'à une baisse des contenus en phosphatidylcholine, phosphatidylethanolamine et en phosphore total phospholipidique. Ces observations démontrent l'altération du métabolisme phospholipidique probablement au niveau de la biosynthèse. L'oxydation des acides gras à longues et à courtes chaines est également altérée lors de la déplétion phosphatée, ce qui démontre encore l'anomalie du métabolisme lipidique. Ce métabolisme phospholipidique anormal pourrait être compatible avec les modifications de la membrane cellulaire décrits au cours de la déplétion phosphatée.

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