Apolipoproteins C in very low density lipoproteins (VLDL) in idiopathic hyperlipoproteinaemia

The purpose of this study was an assessment of the relative proportions of apolipoprotein C subfractions in the VLDL fraction, which could contribute to explaining the development of metabolic disturbances in hyper-pre-beta-lipoproteinaemias. The study was carried out in 21 patients with hyperlipoproteinaemia type IIa, IIb, III, IV and in 8 subjects without lipid metabolism disturbances. Apolipoproteins C were separated in disc electrophoresis on polyacrylamide gel (PAGE) with added 8-M of urea. After the electrophoresis three main subfractions were obtained and were identified according to their electrophoretic mobility as Apo CII, Apo CIII1 and Apo CIII2. The relative per cent proportions of apolipoproteins C were determined by densitometry. A correlation was found between triglyceride concentration in the VLDL fraction and the relative amounts of Apo CII and Apo CIII1. Moreover, a raised ratio of the lipoprotein lipase inhibitor (Apo CIII1) to the activator of this enzyme (Apo CII) was demonstrated in hyperlipoproteinaemias type IIb, III and IV, which may suggest decreased susceptibility of these lipoproteins to the action of lipoprotein lipase.