Human Thromboxane A2 ELISA kit

Tetrahydroxystilbene glucoside (TSG) is the main water-soluble component in Polygonum multiflorum Thunb, and it has many cardioprotective effects. Although TSG is able to relax blood vessels, its relaxation of rat superior mesenteric arteries and the underlying mechanism of this process are not clearly understood. The aim of the present study was to use in vivo and in vitro models to investigate the arterial relaxation effect of TSG on rat superior mesenteric arteries and the mechanisms involved. We found that TSG concentration-dependently relaxed the superior mesenteric artery with or without endothelium. The vasorelaxation induced by TSG is not related to the vasodilator derived factor NO but is rather by the inhibition of COX-2 activity and decreased TXA(2). We also found that the vasorelaxation induced by TSG was attenuated by 4-AP. Moreover, TSG also inhibited the contraction induced by an increase in external calcium concentration in Ca2+-free medium plus KCl (60 mM). These results suggest that TSG induces relaxation in mesenteric arterial rings through an endothelium-dependent pathway that involves the inhibition of COX-2 activity and decreased in TXA(2) and through an endothelium-independent pathway via opening of a voltage-dependent K+ channel, blockade of Ca2+ influx and release of intracellular Ca2+.

Objective: To evaluate the effects of ticagrelor and high-dose clopidogrel on the platelet functions in patients with inadequate response to clopidogrel. Methods: In this prospective, randomized and controlled study, patients who had been diagnosed as acute coronary syndrome (ACS) with inadequate response to clopidogrel in the Second Hospital of Hebei Medical University from July 2015 to June 2016 were enrolled. Inadequate response to clopidogrel was defined as absolute reduction of platelet aggregation rate (PAR) < 30% or PAR > 70%. Eligible patients were randomly assigned to two groups, the high-dose group and the ticagrelor group. Clinical information and intervention protocols were compared. The PAR of the two groups were measured at the time of baseline, the 24th hour, 72nd hour, and the 7th day after treatments, the other platelet-related parameters were measured including platelet count (PLT), mean platelet volume (MPV), platelet distribution width (PDW) at the same time points. Besides, the markers of platelet activation human P-selectin (CD62P) and thromboxane A2 (TXA2) were also recorded to compare. The incidence of major adverse cardiac events (MACE) and the side effects between two groups were followed up for three months. Results: A total of 74 patients were finally enrolled, 38 of whom were assigned to the ticagrelor group and the rest of them to the high-dose clopidogrel group. The baseline clinical and procedural characterists were similar. There were no significant differences in baseline levels of PAR between the two groups [(79.38 +/- 11.20)% vs. (73.97 +/- 12.74)%, P> 0.05]. For both groups, the levels of PAR significantly decreased at each time point (P< 0.001). Besides, the levels of PAR in ticagrelor group were lower than those in high-dose clopidogrel group at the 24th hour, 72nd hour and 7th day after treatments: [(25.92 +/- 10.31)% vs. (37.95 +/- 11.63)%, P< 0.001], [(28.02 +/- 14.61)% vs. (30.64 +/- 10.73)%, P< 0.001], [(37.17 +/- 11.11)% vs. (36.80 +/- 7.26)%, P< 0.001]. The baseline levels of platelet related parameters were similar between the two groups (P> 0.05), and there were no significant differences in the levels of PLT, PDW, and MPV at the 24th hour, 72nd hour and 7th day. It was lower in ticagrelor group than that in clopidogrel group at the 24th hour [(5.47 +/- 1.03) ng/ml vs. (8.02 +/- 1.45) ng/ml, P< 0.001] while the CD62P concentrations in the two groups significantly decreased comparing to the baseline levels (P< 0.001). During 3-month follow-up, the incidences of MACE and side effects were not significantly different between the two group. Conclusions: ticagrelor could further decrease levels of platelet aggression rate and CD62p compared with highdose clopidogrel, without serious side effects.