Résumé
Aim: The purpose of this study was to observe the effect of 15-HETE on rabbit pulmonary artery (PA) vasoconstriction after removing extracellular Ca2+ and on [Ca2+]i in PASMCs and to discuss the mechanisms of cytosolic Ca2+ mobilization induced by 15-HETE. Methods: We used tention studies of PA rings to observe the effect of L-type Ca2+ channel blocker and non-Ca2+ solution on PA vasoconstriction induced by 15-HETE. Then we used laser-scanning confocal microscope to investigate [Ca2+]i signaling in cultured PASMCs. Results: L-type Ca2+ channel blocker and non-Ca2+ solution had no effect on 15-HETE induced vasoconstriction in normoxic and hypoxic rabbit PA rings. The increase of [Ca2+]i was shown in 15-HETE group cells and the change in [Ca2+]i induced by 15-HETE was significantly different from that of control. Conclusion: 15-HETE may activate Ca2+ release from intracellular stores and raise [Ca2+]i in PASMCs.
Résumé
Aim To evaluate the effect of 15-hydroxy eicosatetraenoic acid(15-HETE) on the tension of isolated internal carotid artery(ICA) rings in normoxic or hypoxic rats in order to find out the pathophysiological effect of 15-HETE in ischemic/hypoxic brain tissues.Methods Sixteen healthy Wistar rats were randomly divided into two groups(n=8): group A with normal oxygen supply(FiO_2 21%) and group B with hypoxia(FiO_2 10%).9 days later,the rats were killed and the ICA rings were prepared.15-HETE in different concentration were added accordingly,and the after washing up,blockers of different kinds of K~+ channels such as 2 mmol?L~(-1) 4-AP,10~(-2) mol?L~(-1) TEA and 10~(-6) mol?L~(-1) GLYB were added to the KH solution separately,followed by the administration of 10~(-6) mol?L~(-1) 15-HETE.The isometric tension was recorded using a four-channel force-displacement transducer.Results The ICA tension was significantly increased both in groups A and B by 15-HETE in concentration-dependent manner(P0.05,n=8).Furthermore,10~(-2) mol?L~(-1) TEA,10~(-6) mol?L~(-1) GLYB had little effects on the tension of rings.Application of 10~(-6) mol?L~(1) 15-HETE after administration of TEA or GLYB induced nearly the same increase in ICA tone as it happened in the group administered with 10~(-6)mol?L~(-1) 15-HETE alone.Conclusion 15-HETE can induce brain vasoconstriction especially under the hypoxic condition.Voltage-dependent potassium channels play an important role in 15-HETE induced constriction.
Résumé
Aim To test the contribution of 15-HETE on expression of KV1.5 channel under hypoxia condition,using CDC or NDGA to block 15-LO/15-HETE,and to observe the effect of hypoxia on KV1.5 channel protein,mRNA expressions in cultured rat pulmonary arterial smooth muscle cells(PASMCs)and pulmonary arterials(PAs).Methods Western blot,RT-PCR and 15-LO blockers,cinnamyl 3,4-dihydroxy-[alpha]-cyanocinnamate(CDC)or nordihydroguiairetic acid(NDGA)were used to identify the role of endogenous 15-HETE on expression of KV1.5 channel in cultured rat pulmonary arterial smooth muscle cells(PASMCs)and PAs.Results(1)The expressions of KV1.5 channel protein and mRNA in PASMCs and PAs preteated with CDC or NDGA greatly increased than those of PASMCs under hypoxia group.(2)Exogenous 15-HETE added to PASMCs pretreated with CDC or NDGA greatly decreased the expression of KV1.5 than that of adding PASMCs pretreated with CDC or NDGA under hypoxia condition.Conclusion The down-regulation of KV1.5 channel expression caused by hypoxia is through endogenous 15-HETE.
Résumé
Aim The purpose of this study was to compare the effect of AA、15-HETE、15-KETE and 8(S),15(S)-DiHETE on hypoxic and normoxic rabbit pulmonary arterial rings and to discuss their roles in the formation of PA hypertension.Methods Twelve neonatal rabbits were randomly divided into two groups(n=6):the normoxic group breathing fresh gas(FiO_2 =21%) and the hypoxic group breathing hypoxic gas(FiO_2=10%).After 9 days,they were anesthetized with pentobarbital sodium,and the chest was opened for removal of the heart and lungs en bloc,then PA rings(0.5~1.5 mm in diameter and 3 mm length) were prepared.We used tension studies of PA rings to observe the effect of AA、15-HETE、15-KETE and 8(S),15(S)-DiHETE on hypoxic and normoxic rabbit pulmonary arterial rings.Results ① AA、15-HETE、15-KETE and 8(S),15(S)-DiHETE constricted normoxic rabbit PA rings in a dose-dependent manner,respectively.Constriction of normoxic rabbit PA rings induced by 15-KETE、8(S),15(S)-DiHETE was significant,but that of AA、15-HETE wasn′t significant.② AA、15-HETE、15-KETE and 8(S),15(S)-DiHETE increased hypoxic rabbit PA rings' tension.Constriction of AA、15-HETE on rabbit PA rings in hypoxic group was significantly greater than that of normoxic group(P0.05).③ Constriction of 15-KETE on rabbit PA rings in normoxic group was significantly greater than that of hypoxia group(P