Effect Of Hydrogen-saturated Saline On Platelet Activation In Sinoaortic Denervation Rats And The Underlying Mechanism

BackgroudIn hypertension, blood pressure variability(BPV)increased, which may leadto thrombotic target organ damage. Platelet activation plays an important role inthrombogenesis. An rat model of enhanced BPV was induced by sinoaorticdenervation(SAD). SAD rats exhibited a marked increase in BPV with nochange in the average level of blood pressure(BP)AimsThis study was designed to investigate the effect of enhanced BPV onplatelet activation and the underlying mechanism.Moreover, the effect ofhydrogen-saturated saline on platelet activation induced by enhanced BPV wasstudied.MethodsIn vivo experiments, rats were divided into sham operation group, SADgroup, hydrogen-saturated saline group, Vc group, Vc+hydrogen-saturatedsaline group. Except the sham group, the other four groups underwent SADsurgery. Sham group and the SAD model group were given a hydrogen saturatedsaline solvent (10ml·kg-1·d-1, ip); hydrogen-saturated saline group was treatedwith saturated hydrogen saline (10ml·kg-1·d-1, ip); Vc group was given vitaminC injection liquid (250mg·kg-1, use the menstruum make up to10ml·kg-1·d-1,intraperitoneal injection); hydrogen-saturated saline plus Vc group was givenvitamin C (250mg·kg-1,use the hydrogen saturated-saline complement to10ml·kg-1·d-1, intraperitoneal injection). After4or8weeks treatment, measurethe changes of SBP, DBP, MBP, SBPV, DBPV and MBPV were monitored inconsciouse, freely moving rats. Platelet aggregation was induced by ADP andcollagen.Platelet adhesion to collagen was determined in high shear rates (1080s-1) and low shear rate (300s-1). The expression of CD62P on plateletsurface was measured with flow cytometry.Additionally, levels of TXB2, MDAand NO was detected with radioimmunoassay and UV spectrophotometry. Invitro experiments, the model with enhanced BPV was established.There weredivided into normal fluctuating group, fluctuating group, saturated hydrogensaline group, Vc group, and Vc+hydrogen-saturated saline group. They weretreated with normal saline, hydrogen-saturated saline, Vc or four or Vc+hydrogen-saturated saline for ten minutes respectively.Platelet adhesion tocollagen was determined in low shear rate (300s-1). The expression of CD62P onplatelet surface, ROS and NO in platelet,and platelet microaggregation wasmeasured with flow cytometry.Results1. Hemodynamic changes: In vivo experiments, compared with the shamoperation group, SBP, DBP, MBP was not significantly changed in SADgroup,whereas SBPV, DBPV, MBPV were significantly increased.Similarly,invitro experiments, compared with normal fluctuating group, there was nosignificant change in fluctuating group, of SBP, DBP, MBP was no significantdifference, whereas SBPV, DBPV, MBPV were significantly increased.2. Platelet function changes: In vivo experiment results, compared with thesham operation group, P-selectin expression on platelet surface, plateletadhesion rate in high shear rate and low shear rate, platelet aggregation inducedby ADP and collagen, plasma TXB2levels were elevated significantly in SADgroup. Similarly, in vitro experiments, compared with normal fluctuating group,there was significant increase in P-selectin expression on platelet surface,platelet aggregation and micro aggregation induced by ADP, platelet adhesion tocollagen in low shear rate (300s-1) was increased significantly in fluctuatinggroup.3. Detection ofoxidative stress and NO: Compared with the sham group,plasma MDA content increased and plasma NO level decreased in SAD group.Similarly, compared with normal fluctuating group, mean fluorescence intensityof ROS in platelet was increased significantly, and that of NO in platelet wasdecreased significantly in fluctuating group.4. Intervention effects of hydrogen-saturated saline on platelet activationinduced by increased BPV: In vivo experiments, compared with SAD group, P-selectin expression on platelet surface, platelet adhesion rate in high shearrate and low shear rate, platelet aggregation induced by ADP and collagen,plasma TXB2and MDA levels were reduced significantly, and plasma NO levelwere increased significantly in hydrogen-saturated saline group, Vc group,Vc+hydrogen-saturated saline group. Similarly, in vitro experiments, comparedwith fluctuating group, there was significant decrease in P-selectin expressionon platelet surface, platelet aggregation and micro aggregation induced by ADP,platelet adhesion to collagen in low shear rate (300s-1) and mean fluorescenceintensity of ROS in platelet was decreased significantly, and mean fluorescenceintensity of NO in platelet was increased significantly in fluctuating group.ConclusionsEnhanced BPV may lead to platelet activation with increase of oxdative stressand decrease of NO level in platelet. Hydrogen-saturated saline may inhibiteplatelet activation induced by enhanced BPV. This intervention effects may berelated to decrease of oxdative stress and increase of NO level in platelet.