Aspects of the regulation of liver lipase

It is evident that factors that influence the activity of liver lipase could be important because of the role of liver lipase in HDL-cholesterol metabolism. At the start of this study not much was known about the regulation of liver lipase. The activity had been found to be decreased after fasting (10,34), during hypercortisolism {12), hypothyreoidism {35). insulin deficiency in diabetes {35,12) and by estrogen treatment {36) suggesting a role for respectively insulin~ corticosteroids, thyroxine and estrogens in the regulation of the activity of the enzyme, respectively. This thesis describes the effects of several hormones (corticosteroids, catecholamines, insulin, thyroxin) on the liver lipase activity in vivo and in vitro. In chapter II and appendix paper I the model used to study the regulation of liver lipase in vitro is shown in addition to several factors influencing the liver lipase activity in vitro. Aspects of the regulation of liver lipase in vivo are described in chapter III including the turnover of liver lipase and the influence of essential fatty acid (EFA) deficiency. In chapter IV factors influencing the enzyme activity are discussed by an integration of literature data with our own experiments