Lipid intermediates in chronically volume-overloaded rat hearts. Effect of diffuse ischemia.

Tissue contents of intermediates of fatty acid metabolism were determined in isolated volume-overloaded rat hearts, 3 months after creation of an aorto-caval fistula. In the absence of any modification of blood carnitine, tissue levels of total carnitine were reduced by 33% in overloaded hearts compared to normal hearts. Total tissue CoA was unchanged. Fifteen minutes of whole-heart ischemia (i.e. a 50% reduction in coronary flow) did not increase levels of long-chain acyl esters of CoA and carnitine of the overloaded myocardium, in the presence of glucose as the only exogenous substrate. This was associated with lower than normal levels of long-chain acyl carnitine under normoxic conditions. The addition of exogenous palmitate (1.5 mM) resulted in an ischemia-induced accumulation of long-chain acyl-CoA and acyl carnitine in the overloaded heart although to a smaller extent than in the normal heart under similar perfusion conditions.