TABLE 3.

Increased LTIP content of LDL reduces its reactivity with CETP

Incubation Time	Plasma LTIP	CETP Activity	CETP Activity
	% on LDL	% transfer	% control
0 h	19.6	9.58 ± 0.43	100
24 h + prx	40.0	7.41 ± 0.27	77.4
24 h	60.8	5.47 ± 0.22	57.1

CETP, cholesteryl ester transfer protein. Fresh plasma was incubated at 37°C for the indicated times in the absence or presence of 1 mM paraoxon (prx) as indicated. The fraction of plasma LTIP associated with LDL was determined from the data shown in Fig. 6. Endogenous CETP activity on LDL was measured by adding [³H]CE-LDL (10 μg cholesterol) to incubated plasma samples (50 μl) and further incubating 4.5 h at 37°C. Subsequently, the extent of [³H]CE transfer from LDL to HDL was determined by precipitating apolipoprotein B-containing lipoproteins with manganese chloride in the presence of phosphate buffer (21), then quantifying the ³H content of the supernatant. CETP activities are the mean ± SD (n = 5).