The regulatory events whereby the amount of secreted heart lipoprotein lipase decreases post-prandially and increases during fasting are unclear. We examined whether the nutritional state influenced the lipolytic activities that hydrolyze tri-, di-, and monoacylglycerol as membrane-associated enzyme in rat cardiomyocytes. Properties of triacylglycerol lipase are typical of lipoprotein lipase whereas diacylglycerol and monoacylglycerol lipase activities hydrolyze the products of lipoprotein lipase action. We observed that: (1) membrane-bound activity levels assayed at the cell boundary were high for MAGL and much lower for TAGL and DAGL, regardless of whether cells originated from fasted or fed rats; (2) the stimulatory effects of serum were likewise similar in the fasted and the fed states; (3) isolated cardiomyocytes exhibited no constitutive secretion of active enzyme; and (4) factors determining the variations in amounts of heparin-releasable enzyme in response to nutritional changes appeared to be related to the pre-existing high (in the fasted state) or low (in the fed state) intracellular content in enzymatic activities, supporting the proposal that the secretion of active lipoprotein lipase involves disruption of intracellular vesicles and exocytosis of the enzyme, without its accumulation in the plasma membrane. On a functional basis, the results emphasize the heterogenous nature of the LPL enzymatic complex.