Impaired very low density lipoprotein and triglyceride removal in broad beta disease: comparison with endogenous...

The removal rate of apoprotein-B (apo B) in very low density lipoprotein (VLDL) was decreased in individuals with broad beta disease when compared with endogenous hypertriglyceridemia. Following the injection of 125I-VLDL isolated from individuals with endogenous hypertriglyceridemia, both VLDL apo B fractional catabolic rate (0.058 +/- 0.029 hr-1) and VLDL apo-B turnover rate (0.300 +/- 0.070 mg/kg/hr) were lower in broad beta disease than in endogenous hypertriglyceridemia (fractional catabolic rate 0.112 +/- 0.046, p less than .05; turnover rate 0.640 +/- 0.199, p less than .005) despite equivalent plasma concentrations of VLDL-apo-B. Furthermore, conversion of VLDL apo-B to LDL was impaired in broad beta disease relative to endogenous hypertriglyceridemia. Differences in the kinetics of lipoprotein lipase-related triglyceride removal during a maximal heparin infusion were also demonstrated between these two disorders. These differences suggest an abnormality in the interaction of lipoprotein lipase with the lipoproteins of unusual composition in broad beta disease. This is further supported by the normalization of lipoprotein composition in broad beta disease by estrogen therapy, with a simultaneous change in the kinetics of lipoprotein lipase-related triglyceride removal towards those seen in endogenous hypertriglyceridemia.