Fig. 5
LPS amplifies ADP-mediated thromboxane B2 (TxB2) secretion and inhibition of platelet cyclooxygenase 1 attenuates LPS-mediated alpha-granule secretion. a Platelet TxB2 concentration was measured by ELSIA from platelet supernatant in 10 dogs. In the presence or absence of ADP, platelets were treated with 5 μg/ml LPS. Thrombin-stimulated and acetyl salicylic acid (ASA)-treated platelets served as positive and negative controls, respectively. LPS-treated platelets did not augment TxB2 production compared to unstimulated platelets and ADP-treated platelets. ADP priming in LPS-treated platelets led to more TxB2 than ADP-treated platelets, LPS-treated platelets and unstimulated platelets. b,c Isolated platelets from 10 dogs were pretreated with 100 μM acetylsalicyclic acid (ASA) prior to treatment with 5 μg/ml LPS with or without ADP. Platelet alpha-granule secretion was assessed by P-selectin (CD62P) measured as percent (%) positive b or mean fluorescence intensity (MFI) fold change c using flow cytometry. ASA significantly decreased the % P-selectin positive platelets a but not P-selectin MFI fold change b in LPS-treated platelets in the absence or presence of ADP-priming. First and third quartiles were represented by the lower and upper boundaries, respectively, and the line within the box represents the median. + represents the mean. Whiskers represent the range of date. * p < 0.05, # Significance between all treatments and controls (p<0.05)