High density lipoprotein₂. Relationship of the plasma levels of this lipoprotein species to its composition, to the magnitude of postprandial lipemia, and to the activities of lipoprotein lipase and hepatic lipase

Lipoprotein lipase (LPL) activity in postheparin plasma of 38 normolipidemic volunteers was related to the magnitude of postprandial lipemia after a fat meal, to triglyceride content of high density lipoprotein₂ (HDL₂) to hepatic lipase (HL) activity, and to HDL₂ levels. LPL activity correlated indirectly with lipemia, triglyceride content of HDL₂, HL activity, and levels of HDL₂ but not of HDL₃. HL activity correlated directly with lipemia and indirectly with HDL₂ levels. Triglyceride content of HDL₂ correlated directly with lipemia and indirectly with HDL₂ levels. In HDL₂, abundance of apolipoprotein (apo) A-II and the apoA-I/apo-II ratio varied widely. The latter correlated positively with LPL activity and HDL₂ levels, and, inversely, with HL activity, lipemia, and triglyceride content of HDL₂. The study suggest that HDL-cholesterol is not an independent parameter of lipid transport, but is strongly affected by triglyceride metabolism through lipolytic enzymes, as exemplified by postprandial lipemia that affect both composition and plasma levels of HDL₂.