Journal of Lipid Research, Vol 32, 251-257, Copyright © 1991 by Lipid Research, Inc.

ARTICLES

Lipoprotein lipase in human milk: compartmentalization and effect of fasting, insulin, and glucose

MC Neville, LJ Waxman, D Jensen and RH Eckel
Department of Physiology, University of Colorado School of Medicine, Denver 80262.

The object of this study was to investigate the effect of maternal metabolic state on the activity of lipoprotein lipase (LPL) in human milk. Although the total LPL activity in milk was not significantly affected by up to three cycles of freezing and thawing, the amount of LPL associated with the cream fraction of the milk increased from an average of less than 10% to about 70% after this treatment. The enzyme was relatively stable when the milk was stored on ice, losing activity at a rate of about 1% per hour. At 37 degrees C degradation was more rapid, about 7% per hour. When LPL activity was measured in samples taken at hourly intervals by breast pump, using oxytocin to achieve a complete letdown at each pumping, activity was found to double from the first to the third pumping. Thereafter the activity was stable under fasting conditions. Hyperglycemic and euglycemic, hyperinsulinemic glucose clamp protocols were used to evaluate the effects of glucose and insulin. Both high plasma glucose and high plasma insulin in the presence of normal glucose significantly increased LPL activity within 4 hours. We conclude that, like adipose, tissue LPL, mammary LPL is regulated by plasma insulin.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				Y. Chilliard, A. Ferlay, J. Rouel, and G. Lamberet A Review of Nutritional and Physiological Factors Affecting Goat Milk Lipid Synthesis and Lipolysis J Dairy Sci, May 1, 2003; 86(5): 1751 - 1770. [Abstract] [Full Text] [PDF]

				P. Ramos, A. MartÍn-Hidalgo, and E. Herrera Insulin-Induced Up-Regulation of Lipoprotein Lipase Messenger Ribonucleic Acid and Activity in Mammary Gland Endocrinology, March 1, 1999; 140(3): 1089 - 1093. [Abstract] [Full Text]