Phospholipid removal during degradation of rat plasma very low density lipoprotein in vitro1
The hydrolysis of glycerophospholipids in very low density lipoprotein by enzyme(s) released into circulation after the injection of heparin to rats was studied. [32P]Lysolecithin was formed rapidly from [32P]lecithin when very low density lipoprotein, labeled biosynthetically with 32P, was incubate...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Elsevier
1976-11-01
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| Series: | Journal of Lipid Research |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0022227520417298 |
| _version_ | 1818646843124350976 |
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| author | S Eisenberg D Schurr |
| author_facet | S Eisenberg D Schurr |
| author_sort | S Eisenberg |
| collection | DOAJ |
| description | The hydrolysis of glycerophospholipids in very low density lipoprotein by enzyme(s) released into circulation after the injection of heparin to rats was studied. [32P]Lysolecithin was formed rapidly from [32P]lecithin when very low density lipoprotein, labeled biosynthetically with 32P, was incubated with postheparin plasma. The [32P]lysolecithin was associated with the plasma protein fraction of density greater than 1.21 g/ml, whereas [32P]lecithin exchanged between very low and high density lipoproteins. Inhibition of the plasma lecithin: cholesterol acyl transferase activity did not change the excess [32P]lysolecithin formation in postheparin plasma, and only a negligible amount of radioactivity was associated with blood cells when the incubation was repeated in whole blood.Analysis of the results has demonstrated that phospholipids are removed from VLDL by two pathways: hydrolysis of glycerophospholipids by the heparin-releasable phospholipase activity (>50%) and transfer to high density lipoproteins (<50%). The tissue origin of the postheparin phospholipase was studied in plasma obtained from intact rats and supradiaphragmatic rats using specific inhibitors of the extrahepatic lipase system (protamine sulfate and 0.5 M NaCl). The phospholipase activity could be ascribed to both the hepatic and extrahepatic lipase systems.It is concluded that hydrolysis of glycerophospholipids is the major mechanism responsible for the removal of phospholipids from very low density lipoprotein during the degradation of the lipoprotein. It is suggested that phospholipid hydrolysis occurs concomitantly with triglyceride hydrolysis, predominantly in extrahepatic tissues. |
| first_indexed | 2024-12-17T00:53:04Z |
| format | Article |
| id | doaj.art-542b9ba7769a425baa4c97ba81010f82 |
| institution | Directory Open Access Journal |
| issn | 0022-2275 |
| language | English |
| last_indexed | 2024-12-17T00:53:04Z |
| publishDate | 1976-11-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Lipid Research |
| spelling | doaj.art-542b9ba7769a425baa4c97ba81010f822022-12-21T22:09:41ZengElsevierJournal of Lipid Research0022-22751976-11-01176578587Phospholipid removal during degradation of rat plasma very low density lipoprotein in vitro1S Eisenberg0D Schurr1Lipid Research Laboratory, Department of Medicine B, Hadassah University Hospital, Jerusalem, IsraelLipid Research Laboratory, Department of Medicine B, Hadassah University Hospital, Jerusalem, IsraelThe hydrolysis of glycerophospholipids in very low density lipoprotein by enzyme(s) released into circulation after the injection of heparin to rats was studied. [32P]Lysolecithin was formed rapidly from [32P]lecithin when very low density lipoprotein, labeled biosynthetically with 32P, was incubated with postheparin plasma. The [32P]lysolecithin was associated with the plasma protein fraction of density greater than 1.21 g/ml, whereas [32P]lecithin exchanged between very low and high density lipoproteins. Inhibition of the plasma lecithin: cholesterol acyl transferase activity did not change the excess [32P]lysolecithin formation in postheparin plasma, and only a negligible amount of radioactivity was associated with blood cells when the incubation was repeated in whole blood.Analysis of the results has demonstrated that phospholipids are removed from VLDL by two pathways: hydrolysis of glycerophospholipids by the heparin-releasable phospholipase activity (>50%) and transfer to high density lipoproteins (<50%). The tissue origin of the postheparin phospholipase was studied in plasma obtained from intact rats and supradiaphragmatic rats using specific inhibitors of the extrahepatic lipase system (protamine sulfate and 0.5 M NaCl). The phospholipase activity could be ascribed to both the hepatic and extrahepatic lipase systems.It is concluded that hydrolysis of glycerophospholipids is the major mechanism responsible for the removal of phospholipids from very low density lipoprotein during the degradation of the lipoprotein. It is suggested that phospholipid hydrolysis occurs concomitantly with triglyceride hydrolysis, predominantly in extrahepatic tissues.http://www.sciencedirect.com/science/article/pii/S0022227520417298heparin releasable hospholipase activitylipoprotein-phospholipidslysolecithin[32P]lecithin[32P]sphingomyelin“hepatic” and “extrahepatic” lipoprotein lipase |
| spellingShingle | S Eisenberg D Schurr Phospholipid removal during degradation of rat plasma very low density lipoprotein in vitro1 Journal of Lipid Research heparin releasable hospholipase activity lipoprotein-phospholipids lysolecithin [32P]lecithin [32P]sphingomyelin “hepatic” and “extrahepatic” lipoprotein lipase |
| title | Phospholipid removal during degradation of rat plasma very low density lipoprotein in vitro1 |
| title_full | Phospholipid removal during degradation of rat plasma very low density lipoprotein in vitro1 |
| title_fullStr | Phospholipid removal during degradation of rat plasma very low density lipoprotein in vitro1 |
| title_full_unstemmed | Phospholipid removal during degradation of rat plasma very low density lipoprotein in vitro1 |
| title_short | Phospholipid removal during degradation of rat plasma very low density lipoprotein in vitro1 |
| title_sort | phospholipid removal during degradation of rat plasma very low density lipoprotein in vitro1 |
| topic | heparin releasable hospholipase activity lipoprotein-phospholipids lysolecithin [32P]lecithin [32P]sphingomyelin “hepatic” and “extrahepatic” lipoprotein lipase |
| url | http://www.sciencedirect.com/science/article/pii/S0022227520417298 |
| work_keys_str_mv | AT seisenberg phospholipidremovalduringdegradationofratplasmaverylowdensitylipoproteininvitro1 AT dschurr phospholipidremovalduringdegradationofratplasmaverylowdensitylipoproteininvitro1 |