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. Author manuscript; available in PMC: 2023 Nov 17.
Published in final edited form as: Platelets. 2022 Jun 5;33(8):1119–1131. doi: 10.1080/09537104.2022.2078488

Figure 2. Platelet aggregation and granule release are inhibited by ApoA-I.

Figure 2.

A. The maximum light transmission aggregometry (percent) of PRP or WP stimulated with collagen (1 μg/mL) or ristocetin (1.25 mg/mL) after pre-treatment with vehicle control (NS, n=5), apoA-I (n=5), HDL (n=5), SR-BI±apoA-I (n=5), and anti-SR-BI (α-SR-BI) antibody±apoA-I (n=3) expressed as the mean±SEM. ApoA-I, SR-BI + apoA-I, α-SR-BI and α-SR-BI+ apoA-I pretreatments inhibited PRP platelet aggregation to collagen as compared to NS-treated controls (*=p<0.05). Pretreatment of platelets from PRP with α-SR-BI inhibited aggregation to ristocetin vs. controls (*=p<0.05). This inhibition by α-SR-BI inhibition was partially ameliorated by the addition of apoA-I and was significantly increased (‡=p<0.05 vs. α-SR-BI). Preincubation with ApoA-1, SR-BI+apoA-I, α-SR-BI, and α-SR-BI+apoA-I of washed platelets (right) stimulated with collagen showed a significant inhibition vs. controls (*=p<0.05). SB-RI+apoA-I pre-incubation inhibited collagen-induced platelet aggregation compared to SR-BI preincubation alone (†=p<0.05). B. ATP release is shown as the mean±SEM (nM) from PRP samples stimulated with collagen (1μg/mL, left) or ristocetin (1.25 mg/mL, right) after pre-treatment with control (saline, n=5, black bars), apoA-I [300 μg/ml] (n=5, light gray bars), HDL (n=5, darker gray bars), SR-BI +/− apoA-I (n=5, white and darkest gray bars). In response to collagen apoA-I inhibited ATP release as compared to controls (*=p<0.05), SR-BI +apoA-I together inhibited platelet ATP release vs. SAR-BI treated platelets alone (†=p<0.05), and anti-SR-BI antibody-treated platelets released significantly less ATP than control platelets. Ristocetin activation demonstrated that only platelet treated with SR-BI+ ApoA-1 released less ATP than SR-BI-treated platelets alone (†=p<0.05) and antibodies to SR-BI + ApoA-1 released less ATP than controls (*=p<0.05). Statistical significance was determined by Kruskal-Wallis one-way ANOVA with Dunn’s multiple corrections. C. and D. Representative light-transmission aggregation tracings demonstrate reaction after addition of collagen or ristocetin, respectively, of apoA-I treated human samples compared to vehicle treated controls. PRP, platelet rich plasma; WP, washed platelets.