scholarly journals Effects of C apoproteins on the activity of endothelium-bound lipoprotein lipase

1978 ◽  
Vol 175 (3) ◽  
pp. 1143-1146 ◽  
Author(s):  
T W Lukens ◽  
J Borensztajn
Keyword(s):  
Lipoprotein Lipase ◽  
Rat Heart ◽  
Perfused Rat Heart ◽  
Hydrolysis Of

Rat apoprotein C-II activated the hydrolysis of triacylglycerol in apoprotein-depleted chylomicrons by lipoprotein lipase in vitro and in the perfused rat heart. Apoproteins C-I and C-III-3 inhibited the hydrolysis of the triacylglycerol moiety in intact and apoprotein C-II-re-activated chylomicrons in vitro, but had no effect on the hydrolysis in situ.

Heparin-released lipolytic and esterolytic activities of human and rabbit plasmas

1961 ◽  
Vol 201 (5) ◽  
pp. 915-922 ◽  
Author(s):  
B. Shore ◽  
V. Shore
Keyword(s):  
Fatty Acids ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Ethyl Esters ◽  
Lipoprotein Lipase Activity ◽  
Hydrolysis Of

The enzymes released into both human and rabbit plasmas by heparin injection hydrolyzed, in addition to triglyceride moieties of lipoproteins, a number of mono- and diglycerides of C16 and C18 fatty acids after in vitro addition of the unemulsified glycerides to the plasma. In human postheparin plasma, these enzymes also hydrolyzed glycerides of butyric and caproic acids. The pure triglycerides and methyl or ethyl esters of C16 and C18 fatty acids were not substrates. The heparin-released activities for the hydrolysis of glycerides added in vitro persisted after all activity for the lipolysis of lipoproteins had been destroyed by heat. These activities also differed from lipoprotein lipase activity with respect to the effects of 1 m NaCl, dialysis, and aging the plasma at 4 C. It appears that heparin releases into the blood more than one enzyme or more than one form of an enzyme which may be involved in a stepwise degradation to fatty acids and glycerol of the triglyceride moieties of lipoproteins of density less than 1.007 g/ml.

scholarly journals Hydrolysis of plasma triacylglycerol-rich lipoproteins from immature and laying hens (Gallus domesticus) by lipoprotein lipase in vitro

1982 ◽  
Vol 206 (3) ◽  
pp. 647-654 ◽  
Author(s):  
H Griffin ◽  
G Grant ◽  
M Perry
Keyword(s):  
Lipoprotein Lipase ◽  
Lipid Composition ◽  
Laying Hens ◽  
Laying Hen ◽  
Dietary Lipid ◽  
Gallus Domesticus ◽  
High Density Lipoproteins ◽  
Plasma Triacylglycerol ◽  
Hydrolysis Of

Very-low-density (VLD) lipoproteins and portomicrons were isolated from the plasma of immature and laying hens and their size, lipid composition and susceptibility to hydrolysis by lipoprotein lipase were compared. In agreement with other studies, VLD lipoproteins from laying hens were found to be smaller and have a different lipid composition than VLD lipoproteins from immature hens. Portomicrons from immature and laying hens had mean diameters of about 150 nm and similar lipid compositions. Hydrolysis of VLD lipoproteins from immature hens, and portomicrons from immature and laying hens, proceeded rapidly until at least 40% of the substrate had been used. In contrast only 1-15% of laying-hen VLD-lipoprotein triacylglycerol was readily hydrolysis occurred slowly. The limited susceptibility of laying-hen VLD lipoproteins appeared to be due to their low content of lipoprotein lipase activator apoprotein, which occurred despite an abundance of activator in the high-density lipoproteins of laying-hen plasma. The results provide further evidence that the liver of the laying hen synthesizes specialized lipoproteins. Their limited susceptibility to hydrolysis by lipoprotein lipase is probably a major factor in ensuring transport of lipid to yolk rather than to other tissues. The form of transport of dietary lipid, however, is similar in immature and laying hens.

Preferential in vivo accumulation of sn-2,3-diacylglycerols in postheparin plasma of rats

1977 ◽  
Vol 55 (10) ◽  
pp. 1075-1081 ◽  
Author(s):  
N. Morley ◽  
A. Kuksis ◽  
A. G. D. Hoffman ◽  
G. Kakis
Keyword(s):  
Portal Vein ◽  
Lipoprotein Lipase ◽  
Hepatic Lipase ◽  
Water Interface ◽  
Substrate Complex ◽  
Enzyme Substrate ◽  
Oil Water ◽  
Hydrolysis Of

The stereochemical course of in vivo hydrolysis of triacylglycerols by lipoprotein lipase was investigated by determining the structure of diacylglycerol intermediates in postheparin plasma of rats which had been fed [3H]glycerol-labeled Intralipid 2 h before an injection of heparin or had been given an injection of a mixture of [3H]glycerol-Intralipid and heparin. During the clearance of both the natural chylomicrons and the artificial emulsion, sn-2,3-diacylglycerols (60–80%) were found to be the dominant enantiomers. Similar results were obtained when the contribution of the hepatic lipase was altered, either by tying off the mesentery artery and portal vein before injection of heparin, or by injection of heparin directly into the portal vein. These findings are consistent with a preferential release of the acyl group from the sn-1 position of the triacylglycerol molecule as demonstrated previously in vitro. A preferential orientation of the substrate in the enzyme–substrate complex or at the oil–water interface is discussed as a possible basis for these effects.

scholarly journals The effect in vitro of high-density lipoprotein on hydrolysis of triacylglycerol by lipoprotein lipase

1981 ◽  
Vol 200 (2) ◽  
pp. 453-456 ◽  
Author(s):  
M P Rogers ◽  
I Hutchinson
Keyword(s):  
Adipose Tissue ◽  
High Density Lipoprotein ◽  
Lipoprotein Lipase ◽  
Bovine Milk ◽  
Density Lipoprotein ◽  
High Density ◽  
Rat Adipose Tissue ◽  
Adipose Tissue Lipoprotein Lipase ◽  
Hydrolysis Of

In an incubation system in vitro with fully activated Intralipid as substrate, rat high-density lipoprotein inhibits the hydrolysis of triacylglycerol by lipoprotein lipase from rat adipose tissue, but does not inhibit hydrolysis by the enzyme from bovine milk. The pattern of inhibition suggests that substrate and high-density lipoprotein may compete for association with rat adipose-tissue lipoprotein lipase.

scholarly journals Part of quercetin absorbed in the small intestine is conjugated and further secreted in the intestinal lumen

1999 ◽  
Vol 277 (1) ◽  
pp. G120-G126 ◽  
Author(s):  
Vanessa Crespy ◽  
Christine Morand ◽  
Claudine Manach ◽  
Catherine Besson ◽  
Christian Demigne ◽  
...  
Keyword(s):  
Small Intestine ◽  
Intestinal Wall ◽  
Intestinal Lumen ◽  
Intestinal Cells ◽  
Biliary Duct ◽  
In Situ Perfusion ◽  
Perfusion Period ◽  
Hydrolysis Of

Rutin and quercetin absorption and metabolism were investigated in rats after in situ perfusion of jejunum plus ileum (15 nmol/min). In contrast to rutin, a high proportion of quercetin (two-thirds) disappeared during perfusion, reflecting extensive transfer into the intestinal wall. Net quercetin absorption was not complete (2.1 nmol/min), inasmuch as 52% were reexcreted in the lumen as conjugated derivatives (7.7 nmol/min). Enterohepatic recycling contribution of flavonoids was excluded by catheterization of the biliary duct before perfusion. After a 30-min perfusion period, 0.71 μM of quercetin equivalents were detected in plasma, reflecting a significant absorption from the small intestine. The differential hydrolysis of effluent samples by glucuronidase and/or sulfatase indicates that the conjugated forms released in the lumen were 1) glucuronidated derivatives of quercetin and of its methoxylated forms (64%) and 2) sulfated form of quercetin (36%). In vitro quercetin glucuronides synthetized using jejunal and ileal microsomal fractions were similar to those recovered in the effluent of perfusion. These data suggest that glucuronidation and sulfatation take place in intestinal cells, whereas no glucurono-sulfoconjugates could be detected in the effluent. The present work shows that a rapid quercetin absorption in the small intestine is very effective together with its active conjugation in intestinal cells.

scholarly journals In Situ Raman Study of Redox State Changes of Mitochondrial Cytochromes in a Perfused Rat Heart

PLoS ONE ◽  
2013 ◽  
Vol 8 (8) ◽  
pp. e70488 ◽  
Author(s):  
Nadezda A. Brazhe ◽  
Marek Treiman ◽  
Barbara Faricelli ◽  
Jakob H. Vestergaard ◽  
Olga Sosnovtseva
Keyword(s):  
Rat Heart ◽  
Redox State ◽  
Perfused Rat Heart ◽  
In Situ Raman ◽  
Raman Study ◽  
State Changes ◽  
Mitochondrial Cytochromes

scholarly journals Action of liproprotein lipase on apoprotein-depleted chylomicrons

1978 ◽  
Vol 175 (1) ◽  
pp. 53-61 ◽  
Author(s):  
T W Lukens ◽  
J Borensztajn
Keyword(s):  
Lipoprotein Lipase ◽  
Physiological Role ◽  
Rat Plasma ◽  
High Density Lipoproteins ◽  
Complete Restoration ◽  
Immobilized Trypsin ◽  
Plasma High Density ◽  
First Time

1. Rat lymph chylomicrons were exposed to soluble and to immobilized trypsin. This treatment caused no detectable changes in the chylomicron structure or lipid composition, but did result in virtually total depletion of all their tetramethylurea-soluble apoproteins. 2. The capacity of these apoprotein-depleted chylomicrons to act as substrate for lipoprotein lipase in vitro and in situ (i.e. isolated perfused rat heart) was decreased by about 90 and 75% respectively, compared with intact chylomicrons. 3. On incubation with rat plasma high-density lipoproteins, trypsin-treated chylomicrons readily acquired a full apoprotein complement. This resulted in the complete restoration of their capacity to act as substrate for lipoprotein lipase both in vitro and in situ. 4. It is suggested that with the use of try,sin-treated chylomicrons it is now possible for the first time to investigate the physiological role that individual apoproteins play in the catabolism of triacylglycerol-rich lipoproteins by lipoprotein lipase.

scholarly journals Rapid effects of isoprenaline, glucagon, pacing and potassium arrest on post-heparin lipoprotein lipase activity in the perfused rat heart

1979 ◽  
Vol 182 (1) ◽  
pp. 253-255 ◽  
Author(s):  
J Simpson
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Rat Heart ◽  
Lipoprotein Lipase Activity ◽  
Perfusion Medium ◽  
Perfused Rat Heart ◽  
Rat Hearts ◽  
Isolated Rat

The amount of lipoprotein lipase activity released by heparin into the perfusion medium of isolated rat hearts could be increased within 60s by isoprenaline, glucagon or pacing. Potassium arrest and propranolol inhibited the effects of isoprenaline and pacing respectively.

In situ electrochemistry of Ru(NH3)63+ in a perfused rat heart

1997 ◽  
Vol 9 (2) ◽  
pp. 135-140 ◽  
Author(s):  
Mark H. Schoenfisch ◽  
Jeanne E. Pemberton ◽  
Marc Ovadia ◽  
Margaret Levy
Keyword(s):  
Rat Heart ◽  
Perfused Rat Heart
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