The effect of a high fat diet on the carnitine content of skeletal and cardiac muscle from streptozotocin-diabetic and control rats

Abstract

Streptozotocin-diabetic (SZ) and control rats were maintained on high fat (HF) or on low fat (LF) diets for a period of two weeks. Skeletal and cardiac muscle were assayed for free fatty acids and for free, short-chain, and long-chain carnitine. The free fatty acid content of both skeletal and cardiac muscle was increased in SZ rats fed the LF diet and was not augmented appreciably by HF feeding. The level of free carnitine was decreased in muscles from diabetic animals maintained on the LF regimen and was unaffected by the HF diet. The amount of long-chain carnitine esters was increased in both skeletal and cardiac muscle from LF-fed SZ rats and decreased in heart from HF-fed diabetic animals. The absolute amounts of free and long-chain carnitine measured in tissue from the LF fed control rats did not differ consistently from those in muscles from HF-fed control rats. However, the long-chain carnitine/free carnitine ratio was elevated significantly in both skeletal and cardiac muscle from the HF-fed control animals, but was not increased in SZ rats maintained on the HF regimen. Together, these data suggest that high fat feeding results in increased lipid utilization in control but not in diabetic rats.