Hormone-stimulated lipolysis in cardiac myocytes

Type L hormone-sensitive lipase (HSL) activity was increased approx. 35% above control in cardiac myocytes incubated for 15 min with 5 nM-adrenaline. Concomitantly. adrenaline-stimulated myocytes had a lower triacylglycerol content, released more non-esterified fatty acid and had a higher intracellular concentration of cyclic AMP than did myocytes incubated without hormone. The lipase activity measured in adrenaline-stimulated and non-stimulated myocytes was stable in acetone/diethyl ether, stimulated by serum and inhibited by NaCl. These properties are consistent with the type L designation of this HSL. The finding that type L HSL is stimulated by adrenaline indicates that the enzyme that is being activated is found in the cell and not associated with an extracellular compartment of the myocardium.