Highly oxidized low-density lipoprotein does not facilitate platelet aggregation

Figure 1.. Oxidation of LDL by hypochlorite. Plasma, LDL, and oxLDL obtained from two batches of pooled plasma (a and b) were analyzed by agarose gel electrophoresis. The tables show protein and lipid concentrations of LDL and oxLDL. For the subsequent experiments of platelet aggregation and the β-TG assay, lot A and lot B were used, respectively LDL, low-density lipoprotein; VLDL, very low-density lipoprotein; HDL, high-density lipoprotein; oxLDL, oxidized low-density lipoprotein; TC, total cholesterol; TG, triglycerides; LDL-C, low-density lipoprotein cholesterol.

Figure 2.. Monitoring of washed platelet aggregation by light transmission. The effect of oxLDL on platelet aggregation was analyzed by light transmission. Platelets obtained from different subjects were used in three experiments with triplicate assays. (a) Representative monitoring profiles of washed platelet aggregation are shown. Relative ratios of light transmission increased between 1 minute and 20 s and 6 minutes (b), and between 6 and 15 minutes (c) compared among Buffer B, LDL, and oxLDL (mean ± standard deviation, n = 3). The relative ratio of Buffer B was defined as 1. *P < 0.05 vs. Buffer B. ADP, adenosine diphosphate; buffer, Buffer B; LDL, low-density lipoprotein; oxLDL, oxidized low-density lipoprotein.

Figure 3.. Monitoring of washed platelet aggregation by laser light scattering. The effect of oxLDL on platelet aggregation was also assessed by laser light scattering in the same experimental conditions as indicated in Figure 2, except that monitoring was only performed for the initial 6 minutes. Washed platelets were obtained from three different subjects (a, b, and c) and aggregation profiles are shown in triplicate (–1, –2 and –3) for each platelet sample. (d) To evaluate the results of the three experiments, the relative ratios of the mean laser light scattering intensity of triplicate data at 6 minutes (data for Buffer B were defined as 1) were used as the result of each experiment. The results are shown as mean ± standard deviation. *P < 0.05 vs. buffer. buffer, Buffer B; LDL, low-density lipoprotein; oxLDL, oxidized low-density lipoprotein.

Figure 4.. Effect of LDL and oxLDL on β-thromboglobulin secretion. Three experiments (a, b, and c) were performed using separately prepared platelet-rich plasma. β-TG values are expressed as the ratio to the baseline level of β-TG (corresponding to 0 minutes of incubation and defined as 1), which was calculated by multiplying 4/5 (for volume correction) by the β-TG level of the supernatant obtained from used platelet-rich plasma (25 × 104 cells/µL platelets) in each experiment. The table under each graph indicates the calculated lipid concentrations derived from platelet-rich plasma in the mixture. β-TG, β-thromboglobulin; buffer, Buffer B; LDL, low-density lipoprotein; oxLDL, oxidized low-density lipoprotein; TC, total cholesterol; TG, triglycerides; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol.

Figure 5.. Effect of LDL and oxLDL on β-TG. The results are shown as the mean ± standard deviation of triplicate assays. β-TG, β-thromboglobulin; buffer, Buffer B; LDL, low-density lipoprotein; oxLDL, oxidized low-density lipoprotein.