Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.34 (lipoprotein lipase)
 7,025 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Wistar male rats, both fed and fasting for 16 h prior to irradiation, were exposed to a single lethal X-ray dose of 387 mC X kg-1 (1 500R). The activity of lipoprotein lipase in white adipose (epididymal) tissue and heart muscle and the concentration of serum triglycerides were determined at 1, 6, 24, 48, and 72 h after radiation exposure. In the early time periods, at 1 and 6 h after exposure, the activity of lipoprotein lipase was decreased in adipose tissue and increased in heart muscle of the irradiated fed rats; in fasting rats it was decreased in heart muscle at 1 h after exposure. The concentration of serum triglycerides was increased at 1 h and decreased at 6 h after exposure in fed rats. In these rats, alterations in serum triglycerides correlated with changes in lipoprotein lipase activity in adipose tissue. Alterations observed at the later time periods were more dependent on the time interval between radiation exposure and the analysis. Lipoprotein lipase activity increased with time after radiation exposure up to the maximal values at 72 h. Fasting prior to and after irradiation substantially modified the response of animals to radiation.
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PMID:The effect of a single lethal x-irradiation exposure on the activity of lipoprotein lipase in the tissues of the rat. 49 96

Cell suspensions prepared from rat hearts were separated by replating into F1, F2 and M cultures, and cultured for 3--11 days. Lipoprotein lipase activity was highest in the F1 cultures which consisted mainly of non-beating, mesenchymal cells. The enzyme activity was released into the medium only after addition of heparin. The release occurred by an initial rapid phase and a continuous slow phase. Both the rapid and the slow release of enzyme activity by heparin were inhibited by about 70% after a 4 h pretreatment with colchicine. Thus, it seems that the vesicular transport is responsible for the translocation of lipoprotein lipase to the cell surface also during the slow process of release. The residual activity in the colchicine treated cultures was higher than in the controls indicating that no inhibition of enzyme synthesis occurred. The slow phase of enzyme release continued also after removal of heparin from the medium but was reduced markedly when protein synthesis was inhibited by cycloheximide. Thus the increase in total enzyme activity encountered after exposure to heparin resulted from stimulation of new enzyme synthesis. The half-time of lipoprotein lipase in the F1 cultures was 35 min and full restoration of enzyme activity was found 60 min after complete removal of cycloheximide from the system. These data indicate that the culture system can be used to study regulation of new enzyme synthesis and its turnover.
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PMID:Lipoprotein lipase of cultured mesenchymal rat heart cells. I. Synthesis, secretion and releasability by heparin. 63 67

Hepatic triglyceride lipase was isolated from human post-heparin plasma by the method of Ehnholm et al. using modifications which increased the specific activity 12-fold to approximately 3,000 mumol of free fatty acid/h/mg of protein. Lipoprotein lipase with similar specific activity was prepared from the same plasma samples using heparin and concanavalin A affinity chromatography. The molecular weight of hepatic triglyceride lipase (69,000) was slightly greater than that of lipoprotein lipase (67,000) as determined by polyacrylamide electrophoresis in sodium dodecyl sulfate-containing buffers. These proteins had identical amino acid compositions, terminal amino acid residues, and tryptic peptide maps. However, the differences previously described regarding optima of pH and ionic strength and the requirement for apolipoprotein CII (only for lipoprotein lipase) were maintained in the highly purified state. It was found that both proteins contain approximately 8% carbohydrate. Antisera prepared in goats selectively precipitated each activity. Other antisera prepared in chickens reacted with both enzymes, suggesting a common antigenic determinant.
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PMID:A comparison of molecular properties of hepatic triglyceride lipase and lipoprotein lipase from human post-heparin plasma. 64 Oct 46

Lipoprotein lipase is heterogeneous, and it was suggested that the enzyme in adipose tissue is transformed from a species of mol. wt. approx. 120000 to forms of much higher molecular weight as it is secreted from the fat-cell. This paper demonstrates that the forms of higher molecular weight are probably artifacts. Enzyme preparations were characterized by gel filtration, by density-gradient centrifugation and by affinity chromatography. The results indicate that the enzyme forms of mol. wt. greater than 120000 result from an association of the enzyme with particulate material. It is therefore necessary to reconsider schemes that have recently been proposed for the synthesis and export of lipoprotein lipase.
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PMID:The heterogeneity of the lipoprotein lipase of rat epididymal adipose tissue. 65 46

This study supports the possibility for multiple subcellular forms of lipoprotein lipase. 1. The total activity of lipoprotein lipase per g of intact epididymal adipose tissue from fed rats is much higher than that from starved rats. 2. The isolated fat-cells of fed and of starved rats have lipoprotein lipase of almost the same activity per g of fat-pads. The isolated fat-cells of starved rats have a much higher proportion of total activity per g of the intact tissue than do those of fed rats. 3. Under the conditions of homogenization used, only a small proportion of the total activity per g of intact tissue from fed rats was associated with the fat layer which floated to the top of the homogenate during low-speed centrifugation. The different proportions of the specific enzyme activity found in each subcellular fraction are described. 4. Lipoprotein lipase from plasma membranes and microsomal fractions from starved and fed rats was purified by affinity chromatography. 5. The total activity of microsomal lipoprotein lipase per g of intact adipose tissue is enhanced by a normal diet. 6. In intact epididymal adipose tissue from fed rats, the activity per g of tissue of lipoprotein lipase of plasma membranes is much higher than that in the same fraction from starved rats. By contrast, the activities per g of tissue in plasma membranes obtained from starved or from fed rats by collagenase treatment were similar.
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PMID:Effect of nutrition on subcellular localization of rat fat-cell lipoprotein lipase. 66 42

Lipoprotein lipase activity was studied in mesenchymal cells isolated from rat hearts and cultured for up to 8 days. The enzyme activity increased markedly between day 3 and 5 while the subsequent increase was less pronounced. Addition of hydrocortisone to complete culture medium resulted in an increase in lipoprotein lipase activity at all stages of culture. Lipoprotein lipase activity did not increase after addition of insulin to the complete culture medium. In the presence of serum-poor medium between day 3 and 6, the increase in lipoprotein lipase activity was much lower than in the presence of complete culture medium. Addition of hydrocortisone and insulin to the serum-poor medium resulted in a significant rise in lipoprotein lipase activity while less consistent effects were obtained after addition of each hormone alone. Transfer of cells to serum-poor medium between day 6 and 7 of culture caused a fall in enzyme activity. Addition of hydrocortisone alone and with insulin restored enzyme activity to control values. No effect on lipoprotein lipase was seen with estradiol, growth hormone, or glucagon when added to serum-containing medium, or serum-poor medium. These results indicate that the lipoprotein lipase of heart is controlled by glucocorticoids and that this control might require the presence of insulin for optimal expression.
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PMID:Lipoprotein lipase of cultured mesenchymal rat heart cells. III. Effect of glucocorticoids and insulin on enzyme formation. 71 72

The activity of post-heparin lipases in patients with alcoholic hepatitis and viral hepatitis was evaluated. Lipoprotein lipase and hepatic triglyceride lipase were differentiated by assay under high and low salt conditions and also by separation on heparin-agarose affinity chromatography columns. The mean activity of hepatic triglyceride lipase in the sera of liver disease patients was only 21-24% of the mean of controls, but lipoprotein lipase in patients' sera was not different from normal levels. Hepatic triglyceride lipase deficiency may partially account for the accumulation of a triglyceride-rich low density lipoprotein in liver disease.
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PMID:Hepatic triglyceride lipase deficiency in liver disease. 86 46

Lipoprotein lipase was determined in 5-day old cell cultures derived from hearts of newborn rats. With the help of the preplating method the cells were subdivided into cultures containing predominantly cardiac myocytes and into those composed mainly of mesenchymal cells. Lipoprotein lipase activity, associated with the mesenchymal cells was ten times higher than the activity found in the cultures containing mainly the myogenic cells. It is suggested that the mesenchymal cells are the progenitors of lipoprotein lipase in rat heart.
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PMID:Rat heart in culture as a tool to elucidate the cellular origin of lipoprotein lipase. 88 55

Two trioleoyl glycerol hydrolases, one of lysosomal origin as determined by a high correlation with the lysosomal marker enzyme, N-acetyl-beta-glucosaminidase, and one having the characteristics of lipoprotein lipase, were measured at varying stages of lesion development in the aortas of cholesterol-fed rabbits. Both lipases were greatly enhanced in atheromatous aortas and were linearly related to lesion severity as measured by total aortic cholesterol. Lipoprotein lipase activities of myocardium and of plasma of cholesterol-fed rabbits were also significantly increased relative to controls. The data suggest that lipoprotein lipase might be a factor regulating cholesterol deposition in the aorta.
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PMID:Effect of cholesterol feeding on arterial lipolytic activity in the rabbit. 90 18

1. Lipoprotein lipase activity was measured in heart homogenates and in heparin-releasable and non-releasable fractions of isolated perfused rat hearts, after the intravenous injection of Triton WR-1339. 2. In homogenates of hearts from starved, rats, lipoprotein lipase activity was significantly inhibited (P less than 0.001) 2h after the injection of Triton. This inhibition was restricted exclusively to the heparin-releasable fraction. Maximum inhibition occurred 30 min after the injection and corresponded to about 60% of the lipoprotein lipase activity that could be released from the heart during 30 s perfusion with heparin. 3. Hearts of Triton-treated starved rats were unable to take up and utilize 14C-labelled chylomicron triacylglycerol fatty acids, even though about 40% of heparin-releasable activity remained in the hearts. 4. It is concluded that Triton selectively inhibits the functional lipoprotein lipase, i.e. the enzyme directly involved in the hydrolysis of circulating plasma triacylglycerols. 5. Lipoprotein lipase activities measured in homogenates of soleus muscle of starved rats and adipose tissue of fed rats were decreased by 25 and 39% respectively after Triton injection. It is concluded that, by analogy with the heart, these Triton-inhibitable activities correspond to the functional lipoprotein lipase.
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PMID:The inhibition in vivo of lipoprotein lipase (clearing-factor lipase) activity by triton WR-1339. 94 35


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