Platelet-activating factor (PAF) exhibits a variety of biological activities and it be thought to involved in various pathophysiological process. In this paper, some studies were summarized about those roles ofPAF in ...Platelet-activating factor (PAF) exhibits a variety of biological activities and it be thought to involved in various pathophysiological process. In this paper, some studies were summarized about those roles ofPAF in a variety productive processes of female of mammalian that inctude fertilization, implantation and parturition, and that was involved in the concentration, synthesis, deiradation and some assay methods of PAF. Therelationship between PAF and early pregnancy factor (EPF) was reviewed.展开更多
The effects of hydrogen peroxide（H<sub>2</sub>O<sub>2</sub>）on endothelial-polymorphonuclear leuko-cyte（EC-PMN）adhesion and their mechanisms were studied in cultured bovine pulmonaryartery ...The effects of hydrogen peroxide（H<sub>2</sub>O<sub>2</sub>）on endothelial-polymorphonuclear leuko-cyte（EC-PMN）adhesion and their mechanisms were studied in cultured bovine pulmonaryartery endothelial monolayers in vitro.H<sub>2</sub>O<sub>2</sub> at various concentrations(10<sup>-3</sup>,10<sup>-2</sup>,10<sup>-1</sup>mol/Lrespectively)stimulated EC-dependent PMN adhesion,of which 10<sup>-2</sup>mol/L H<sub>2</sub>O<sub>2</sub> was the mostpotent one,increasing adhesion to 2.3 times that of the control.Pretreatment of PMNs with SRI63-441,a platelet-activating factor（PAF）receptor antagonist,had no inhibition effect on H<sub>2</sub>O<sub>2</sub>induced EC-PMN adhesion.Pretreatment of ECs with SRI 63-441 before H<sub>2</sub>O<sub>2</sub> exposure signifi-cantly decreased PMN adherence to ECs.Pretreatment of ECs with phospholipase A<sub>2</sub> inhibitorp-bromophenacyl-bromide or calmodulin antagonist chlorpromazine and calcium ion chelate EG-TA obviously decreased H<sub>2</sub>O<sub>2</sub> induced increment of EC-PMN adhesion.These results suggestthat H<sub>2</sub>O<sub>2</sub> may activate ECs,causing the inflow of extracellular calcium or the release of calciumfrom intracellular deposits.Increased intracellar Ca<sup>2+</sup>may bind with calmodulin to activate phos-pholipase A<sub>2</sub>,thus initiating PAF synthesis and promoting EC-PMN adhesion.展开更多
The effects of isoproterenol (IPN) on histamine and platelet-activating factor (PAF)-induced vascular permeability increment in rat skin and in cultured confluent endothelial cell monolayer were investigated. The resu...The effects of isoproterenol (IPN) on histamine and platelet-activating factor (PAF)-induced vascular permeability increment in rat skin and in cultured confluent endothelial cell monolayer were investigated. The results showed that after intravenous administration of 20 mg/kg Evans blue (EB) dye, the intradermal injection of 0. 2 ml PAF(10-7mol/L) or histamine (0. 5 mmol/L) could induce the exudation of 16. 82+2. 05 μg/g tissue and 21. 86+2. 86μg/g tissue of EB respectively into the injected skin. Pretreatment of the rats with intravenous IPN (10 μg/kg) decreased the EB exudation by 56. 2% and 43. 6% respectively. Propranolol (PPN), a β-adrenoceptor blocker, reversed the inhibitory effects of IPN. In rats treated with PPN alone, intradermal injection of PAF and histamine induced significant increase of skin EB exudation in comparison with the control, indicating that catecholamines at physiologic concentration in vivo may have inhibitory effects on vascular permeability. When cultured endothelial cell monolayers were perfused with 1% albumin in Hanks' balanced salt solution the increased fluid flux and protein clearance caused by PAF were significantly decreased by IPN pretreatment. The results confirmed the inhibitory effects of IPN on vascular permeability increment induced by PAF at the cellular level.展开更多
The regulatory effects of phospholipase A2(PLA2) inhibitors, chloroquine and dexamethasone, on the activity of blood PLA2 and its related lipid mediators during endotoxic shock were observed in rabbits. The rabbits we...The regulatory effects of phospholipase A2(PLA2) inhibitors, chloroquine and dexamethasone, on the activity of blood PLA2 and its related lipid mediators during endotoxic shock were observed in rabbits. The rabbits were randomized into 4 groups as follows : The normal control (NC) group consisted of 12 rabbits with sham injection . the endotoxic shork (ES) group of 31 rabbits, the chloquine pretreated (CQ) group of 16 rabbits receiving 3 mg/kg of chlorqouine and the dexamethasone-pretreated (DM) group of 10 rabbits receiving 5 mg/kg of dexamethasone. Blood was sampled before and 5 and 30 min, 1 ,3, 5 and 8 h after the administration of endotoxin for the determination of PLA2, platelet activating factor (PAF) , TXB2 and 6-keto-PGF1α. In addrtion, changes of mean arterial pressure (MAP) and respiratory rate (RR) were also carefully recorded. It was found that the activities of PLA2 and PAF and the levels of TXB2 and 6-keto-PGF1α. were significantly increased after the infusion of endotoxin. CQ and DM markedly suppressed the activities of PLA2 and PAF. The inhibition of CQ on TXB2 and 6-keto-PGF1α was greater than that of DM. Besides, CQ and DM could increase the survival rate of the animals from 48% to 75% (CQ group) and 70% (DM group). These findings suggest that PLA2 inhibitors such as CQ and DM can significantly attenuate the formation of shock mediators such as PLA2, PAF, TXB2 and 6-keto-PGF1α, and so improve the prognosis of the victims of endotoxic shock.展开更多
文摘Platelet-activating factor (PAF) exhibits a variety of biological activities and it be thought to involved in various pathophysiological process. In this paper, some studies were summarized about those roles ofPAF in a variety productive processes of female of mammalian that inctude fertilization, implantation and parturition, and that was involved in the concentration, synthesis, deiradation and some assay methods of PAF. Therelationship between PAF and early pregnancy factor (EPF) was reviewed.
文摘The effects of hydrogen peroxide（H<sub>2</sub>O<sub>2</sub>）on endothelial-polymorphonuclear leuko-cyte（EC-PMN）adhesion and their mechanisms were studied in cultured bovine pulmonaryartery endothelial monolayers in vitro.H<sub>2</sub>O<sub>2</sub> at various concentrations(10<sup>-3</sup>,10<sup>-2</sup>,10<sup>-1</sup>mol/Lrespectively)stimulated EC-dependent PMN adhesion,of which 10<sup>-2</sup>mol/L H<sub>2</sub>O<sub>2</sub> was the mostpotent one,increasing adhesion to 2.3 times that of the control.Pretreatment of PMNs with SRI63-441,a platelet-activating factor（PAF）receptor antagonist,had no inhibition effect on H<sub>2</sub>O<sub>2</sub>induced EC-PMN adhesion.Pretreatment of ECs with SRI 63-441 before H<sub>2</sub>O<sub>2</sub> exposure signifi-cantly decreased PMN adherence to ECs.Pretreatment of ECs with phospholipase A<sub>2</sub> inhibitorp-bromophenacyl-bromide or calmodulin antagonist chlorpromazine and calcium ion chelate EG-TA obviously decreased H<sub>2</sub>O<sub>2</sub> induced increment of EC-PMN adhesion.These results suggestthat H<sub>2</sub>O<sub>2</sub> may activate ECs,causing the inflow of extracellular calcium or the release of calciumfrom intracellular deposits.Increased intracellar Ca<sup>2+</sup>may bind with calmodulin to activate phos-pholipase A<sub>2</sub>,thus initiating PAF synthesis and promoting EC-PMN adhesion.
文摘The effects of isoproterenol (IPN) on histamine and platelet-activating factor (PAF)-induced vascular permeability increment in rat skin and in cultured confluent endothelial cell monolayer were investigated. The results showed that after intravenous administration of 20 mg/kg Evans blue (EB) dye, the intradermal injection of 0. 2 ml PAF(10-7mol/L) or histamine (0. 5 mmol/L) could induce the exudation of 16. 82+2. 05 μg/g tissue and 21. 86+2. 86μg/g tissue of EB respectively into the injected skin. Pretreatment of the rats with intravenous IPN (10 μg/kg) decreased the EB exudation by 56. 2% and 43. 6% respectively. Propranolol (PPN), a β-adrenoceptor blocker, reversed the inhibitory effects of IPN. In rats treated with PPN alone, intradermal injection of PAF and histamine induced significant increase of skin EB exudation in comparison with the control, indicating that catecholamines at physiologic concentration in vivo may have inhibitory effects on vascular permeability. When cultured endothelial cell monolayers were perfused with 1% albumin in Hanks' balanced salt solution the increased fluid flux and protein clearance caused by PAF were significantly decreased by IPN pretreatment. The results confirmed the inhibitory effects of IPN on vascular permeability increment induced by PAF at the cellular level.
文摘The regulatory effects of phospholipase A2(PLA2) inhibitors, chloroquine and dexamethasone, on the activity of blood PLA2 and its related lipid mediators during endotoxic shock were observed in rabbits. The rabbits were randomized into 4 groups as follows : The normal control (NC) group consisted of 12 rabbits with sham injection . the endotoxic shork (ES) group of 31 rabbits, the chloquine pretreated (CQ) group of 16 rabbits receiving 3 mg/kg of chlorqouine and the dexamethasone-pretreated (DM) group of 10 rabbits receiving 5 mg/kg of dexamethasone. Blood was sampled before and 5 and 30 min, 1 ,3, 5 and 8 h after the administration of endotoxin for the determination of PLA2, platelet activating factor (PAF) , TXB2 and 6-keto-PGF1α. In addrtion, changes of mean arterial pressure (MAP) and respiratory rate (RR) were also carefully recorded. It was found that the activities of PLA2 and PAF and the levels of TXB2 and 6-keto-PGF1α. were significantly increased after the infusion of endotoxin. CQ and DM markedly suppressed the activities of PLA2 and PAF. The inhibition of CQ on TXB2 and 6-keto-PGF1α was greater than that of DM. Besides, CQ and DM could increase the survival rate of the animals from 48% to 75% (CQ group) and 70% (DM group). These findings suggest that PLA2 inhibitors such as CQ and DM can significantly attenuate the formation of shock mediators such as PLA2, PAF, TXB2 and 6-keto-PGF1α, and so improve the prognosis of the victims of endotoxic shock.
