Measurements of C Apoprotein Kinetics in Man

There have been few in vivo studies of C apoprotein metabolism in man. Berman et al. (1) have carried out analyses of total C apoprotein kinetics following reinjection of radiolabelled VLDL. The simulated model resembled that for VLDL B apoprotein metabolism, comprising a series of 4 delipidation steps of the triglyceriderich particles during which C peptides become transferred to HDL, producing a final IDL particle which retains a small fraction of the original VLDL C apoprotein. The model did not identify the lipoprotein with which the C peptides entered the circulation, both VLDL and HDL fitting the data, but removal of C protein appeared to occur with HDL. The major aspects of this in vivo model coincided with findings observed consistently during the in vitro lipolysis of VLDL, and with studies of isolated cells and organs.