It has been shown that the rat trabecula carneae is a suitable tissue for use in the study of myocardial metabolism (1,2). Previously, glycogen metabolism of trabecula carneae (3) as well as lipid metabolism of perfused rat hearts (45) was studied. However, to date, a study of the relation between glycogen and total lipid utilization as endogeneous energy stores in myocardial tissue has not been published. In order to undertake such a study in this laboratory, the development of a technique for the simultaneous determination of these two energy stores in the trabecular preparation was developed. The calorimetric techinque of Seifter (6) and Itaya (7), for glycogen and fatty acid analysis, respectively, have been modified by the authors to permit such a study. LMATERIALS 30% KOH. 95% ethanol. 6 N acetic acid. Phosphate buffer, pH 6.8 Chloroform (CHCI,) . Anthrone reagent: 0.2% anthrone in 95% H,SO, prepared daily. Diethyldithiocarbamate solution: 25 mg sodium diethyldithiocarbamate in 4 ml n-butanol, prepared daily.
Cu-TEA solution: 6.45% CU(NO,)~.~H,O, 1 M, triethanolamine, and 1 N acetic acid in the ratio by volume of 10:9:1, respectively, prepared biweekly.
Glucose standard (Sigma) : 0.10 mg/ml. Palmitic acid standard: 0.04-0.07 heq palmitic acid/ml CHCl,.
METHODS
Glycogen Analysis
The trabecula carneae was digested in a centrifuge tube containing 0.6 ml of 30% KOH in a boiling water bath for 20 min. After cooling,