TY - JOUR
T1 - Apolipoprotein B metabolism in normal, type IV, and type V hyperlipoproteinemic subjects
AU - Packard, Christopher J.
AU - Shepherd, James
AU - Joerns, Susan
AU - Gotto, Antonio
AU - David Taunton, O.
N1 - Funding Information:
From the Division of Atherosclerosis and Lipoprotein Research. Department of Medicine. Baylor College of Medicine and The Methodist Hospital, Houston, Tex. Receivedfor publication October 12. 1978. Supported in part by the Lipid Research Clinic Contract NH71-2156 and the National Institute of Health General Clinical Research Center Grant RROO350. Address reprint requests to Dr. C. J. Packard, Department of Biochemistry, Royal Infirmary. Glasgow> G4 OSF, .!.IK. . (0 I980 by Grune & Stratton, Inc. 0026~495/80/2903~002$02.00/0
Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 1980/3
Y1 - 1980/3
N2 - Apolipoprotein B (apoB) metabolism was investigated in four normal, three type IV, and three type V hyperlipoproteinemic subjects. Following injection of autologous radioiodinated very low density lipoprotein (VLDL) the rate of clearance of the apoprotein from this particle and its subsequent appearance in low density lipoprotein (LDL) was measured by frequent apoB specific activity determinations over an 11-day period. The resultant data were analyzed using the SAAM 27 computer program. In the normal subjects, more than 95% of the injected VLDL apoB was rapidly transferred to the LDL density range and accounted for all LDL apoB synthesis in that group. The plasma VLDL apoB concentration in the type IV group was, on average, five times the normal level. This resulted primarily from a doubling of the VLDL apoB synthetic rate associated with a defective or saturated catabolic mechanism. Only 60% of this material subsequently appeared in LDL, while the remainder was catabolized via an LDL-independent pathway. The turnover parameters of LDL apoB were normal in the type IV patients. Type V hyperlipoproteinemic subjects exhibited a 12- to 35-fold increase in plasma VLDL apoB concentration over normal. This again derived from increased VLDL apoB synthesis in the presence of defective removal of the apoprotein; the fractional catabolic rate of VLDL apoB in this group was 14% of the normal value. However, in contrast to the type IV patient data, more than 85% of the apoB in type V VLDL eventually appeared in LDL whose turnover rate was raised as a result of an increase in its catabolism; the fractional catabolic rate of LDL apoB in type V patients was four-fold above normal. The plasma LDL apoB pool size was substantially reduced in these subjects. This study shows that in hyperlipoproteinemic pheno-types IV and V there exist multiple anomalies of apoB metabolism affecting both VLDL and LDL.
AB - Apolipoprotein B (apoB) metabolism was investigated in four normal, three type IV, and three type V hyperlipoproteinemic subjects. Following injection of autologous radioiodinated very low density lipoprotein (VLDL) the rate of clearance of the apoprotein from this particle and its subsequent appearance in low density lipoprotein (LDL) was measured by frequent apoB specific activity determinations over an 11-day period. The resultant data were analyzed using the SAAM 27 computer program. In the normal subjects, more than 95% of the injected VLDL apoB was rapidly transferred to the LDL density range and accounted for all LDL apoB synthesis in that group. The plasma VLDL apoB concentration in the type IV group was, on average, five times the normal level. This resulted primarily from a doubling of the VLDL apoB synthetic rate associated with a defective or saturated catabolic mechanism. Only 60% of this material subsequently appeared in LDL, while the remainder was catabolized via an LDL-independent pathway. The turnover parameters of LDL apoB were normal in the type IV patients. Type V hyperlipoproteinemic subjects exhibited a 12- to 35-fold increase in plasma VLDL apoB concentration over normal. This again derived from increased VLDL apoB synthesis in the presence of defective removal of the apoprotein; the fractional catabolic rate of VLDL apoB in this group was 14% of the normal value. However, in contrast to the type IV patient data, more than 85% of the apoB in type V VLDL eventually appeared in LDL whose turnover rate was raised as a result of an increase in its catabolism; the fractional catabolic rate of LDL apoB in type V patients was four-fold above normal. The plasma LDL apoB pool size was substantially reduced in these subjects. This study shows that in hyperlipoproteinemic pheno-types IV and V there exist multiple anomalies of apoB metabolism affecting both VLDL and LDL.
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U2 - 10.1016/0026-0495(80)90062-1
DO - 10.1016/0026-0495(80)90062-1
M3 - Article
C2 - 7374435
AN - SCOPUS:0018857761
SN - 0026-0495
VL - 29
SP - 213
EP - 222
JO - Metabolism
JF - Metabolism
IS - 3
ER -