Effect of fasting on the esterfied α-glycerol ethers of the neutral lipids of heart and adipose tissue of rats

Abstract

The effect of prolonged fasting on the lipids of cardiac muscle and adipose tissue of adult rats has been studied with special emphasis on the acylated α-glycerol ethers of the neutral lipids. Adipose tissue was found to be an excellent source of neutral lipid glycerol ethers as well as plasmalogens, the latter being present in amounts previously observed only in brain. In the neutral lipids of adipose tissue 75–80 per cent of the total glycerol ethers were present as ether diesters. The remaining 20–25 per cent of the glycerol ethers consisted of ether monoesters and α-glycerol ethers in similar amounts. In contrast, the triacyl glycerides represented 97 per cent of the total glycerides of adipose tissue. Fasting has little effect on the total glycerol ether content of adipose tissue and cardiac muscle, but results in marked changes in the triacyl glyceride content of these tissues. The concentration of neutral glycerides was found to increase in cardiac muscle only while the stores of triacyl glycerides in adipose had not been depleted. Once the neutral glycerides of adipose tissue started to decrease precipitously, the endogenous glycerides of cardiac muscle declined, suggesting that the non-esterified fatty acid content of the plasma was no longer sufficient to meet the energy needs of the cardiac muscle cell.