Coordinate changes in levels of human serum low and high density lipoprotein subclasses in healthy men.

Measurement of serum lipoproteins by analytic ultracentrifugation revealed significant correlations involving subfractions of low density (LDL) and high density (HDL) lipoproteins in 81 men studied cross-sectionally at baseline and longitudinally during a 1-year exercise trial. One-year changes in lipoprotein levels in 38 exercising men and in 30 sedentary controls showed correlations that paralleled those observed at baseline. Positive correlations observed between plasma levels of larger, more buoyant LDL of flotation rate (Sof) 7 to 10 (LDL-I) and HDL2 may be due to processes that also coregulate changes in levels of these lipoprotein subclasses. Similarly, positive correlations among smaller, more dense LDL of Sof 2 to 6 (LDL-III), IDL, and HDL3 suggest that levels of these lipoprotein species are also coordinately regulated. An inverse correlation of change in LDL-I with change in LDL-III raises the possibility of precursor-product relationships between LDL in these categories. Thus, changes in lipoproteins which are related to coronary disease risk are not independent of one another, and the development of coronary disease may be influenced by processes linking the metabolism of individual IDL, LDL, and HDL components.