Effect of altered cardiac metabolism and work on lipoprotein lipase activity of heart.

MALLOV, SAMUEL, AND ADAWIA A. ALOUSI. Effect of altered cardiac metabolism and work on lipoprotein lipase activity in heart. Am. J. Physiol. 2 I 2 (5) : I I 58-1 I 64. I g67.-Increased cardiac metabolism and/or work were induced in rats by: a) chronic administration of 2 ,4-dinitrophenol, b) aortic constriction, and c) production of hypertension with deoxicorticosterone (DCA) and salt. Decreased cardiac metabolism and work were effected by treating the animals with propylthiouracil so as to bring them into a hypothyroid state. Lipoprotein lipase (LPL) activities of homogenates of the hearts of these rats and of corresponding control animals were then determined. Propylthiouracil-induced hypothyroidism was found to be associated with significantly decreased cardiac LPL activity and chronic DNP administration with significantly increased cardiac LPL activity, but aortic constriction and DCA-salt-induced hypertension did not affect this activity. It is concluded that increase in heart work or development of work hypertrophy per se is not a sufficient stimulus to induce a rise in cardiac LPL activity and that a modification of some specific aspect of cardiac metabolism may provoke changes in LPL activity in heart.