title: Lipoprotein particle abnormalities and the impaired lipolysis in renal insufficiency.
abstract: BACKGROUND
  Increased concentrations of very low- (VLDL) and intermediate-density (IDL) lipoproteins in chronic renal failure (CRF) are thought to result from a defect(s) in degradation of plasma triglyceride (TG)-rich lipoproteins. The purpose of this study was to identify lipoprotein abnormalities associated with the reduced lipolytic rate constant, k1, of combined VLDL and IDL substrate from renal patients and asymptomatic controls.
  
  
  METHODS
  The VLDL + IDL were isolated from 18 predialytic patients (CRF-I), 8 patients on hemodialysis (CRF-II) and 10 asymptomatic controls. The lipolytic rate constant (k1) of VLDL + IDL was measured by an assay using bovine milk lipoprotein lipase and determination of TG before and after incubation by gas chromatography (GC). Neutral lipids were measured by GC and apolipoproteins by electroimmunoassays; the apolipoprotein-defined TG-rich lipoproteins including Lp-B:C, Lp-B:C:E and Lp-A-II:B:C:D:E were determined by immunoaffinity chromatography.
  
  
  RESULTS
  The k1 values of VLDL + IDL were significantly (P < 0.001) lower in CRF-I and CRF-II patients (0.0341 and 0.0352 min-1, respectively) than controls (0.0515 min-1). The levels of apolipoproteins B, C-III and E, and TG-rich Lp-B:C, Lp-B:C:E and Lp-A-II:B:C:D:E particles normalized to 100 mg TG per VLDL + IDL were significantly higher in both groups of CRF patients than in controls. All three TG-rich lipoproteins were characterized by significantly increased percent contents of free (FC) and esterified (CE) cholesterol and a decreased percentage of TG. The k1 values of the combined CRF-I and CRF-II patient groups showed significant negative correlations (P < 0.001) with FC (r=-0.81) and CE (r=-0.63) and a positive correlation with TG (r=0.72). Among lipoprotein particles, only Lp-A-II:B:C:D:E levels showed a significant negative correlation with k1 values (r=-0.47, P < 0.03).
  
  
  CONCLUSIONS
  This study shows that the abnormal neutral lipid composition of all three TG-rich lipoprotein particles and increased concentrations of Lp-A-II:B:C:D:E particles represent the main factors affecting the in vitro lipolytic rates of VLDL + IDL substrate in both the CRF patients before dialysis and patients on hemodialysis.
authors.affiliation: Department of Obstetrics & Gynecology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA. Diane-Lee@omrf.ouhsc.edu
authors.forename: Diana M
authors.initials: DM
authors.lastname: Lee
authors.forename: Carolyn
authors.initials: C
authors.lastname: Knight-Gibson
authors.forename: Ola
authors.initials: O
authors.lastname: Samuelsson
authors.forename: Per-Ola
authors.initials: PO
authors.lastname: Attman
authors.forename: Chi-Sun
authors.initials: CS
authors.lastname: Wang
authors.forename: Petar
authors.initials: P
authors.lastname: Alaupovic
mesh_terms: D000328:Adult; D001053:Apolipoproteins / Q000097:blood; D002784:Cholesterol / Q000097:blood*; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D015243:Cholesterol, VLDL / Q000097:blood; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000378:metabolism* / Q000628:therapy; D007700:Kinetics; D008066:Lipolysis / Q000502:physiology*; D008074:Lipoproteins / Q000097:blood*; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D014280:Triglycerides / Q000378:metabolism; D014511:Uremia / Q000378:metabolism / Q000628:therapy
chemical_list: D001053:Apolipoproteins; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D015243:Cholesterol, VLDL; D008074:Lipoproteins; D014280:Triglycerides; C030104:lipoprotein cholesterol; D002784:Cholesterol