Lipid composition of cardiac lymph.

Cardiac lymph was obtained from fasting dogs by cannulating the efferent collecting trunks and the interventricular (subepicardial) trunk. The total lipid content of the lymph was 450 mg/100 ml and consisted of 16-20% cholesterol, 30-33% triglycerides, 41% phospholipids, 2% free fatty acids, and 7-8% fatty acids esterified with cholesterol. The lipid composition of the lymph obtained from the two collecting sites was identical. We can demonstrate that the loss of total fatty acids by the myocardium due to the drainage of the interstitial fluid into the lymph represents only 2-8% of the fatty acids used. With the exception of triglycerides, the concentration of all the lipids was higher in the arterial plasma than in the lymph. The concentration of triglycerides in the lymph suggests that triglycerides are contributed from endogenous sources.