渗透压、肾上腺素、激活PKC对血管平滑肌细胞Cl~-运动的影响

目的　探讨血管平滑肌细胞容积性调节Cl- 运动的机制。方法　用Cl- 特异的荧光探针 MEQ及生物荧光双波长影像分析系统 ,观察渗透压、肾上腺素、PKC的激活以及细胞外Cl- 浓度 (Cl- ] o)的改变对容积性调节Cl- 运动的影响。结果　A10细胞静息时胞质氯离子浓度 (Cl- ] i)为(3 0 3 9± 3 0 1)mmol·L- 1(n =3 0 ) ;低渗条件使Cl- 外流 ,Cl- ] i 由静息时 (3 0 87± 3 11)mmol·L- 1降低到 (2 4 3 9±2 56)mmol·L- 1(n =3 0 ,P <0 0 5) ;高渗时则从 (2 4 3 9±2 56)mmol·L- 1增加到 (3 4 64± 3 46)mmol·L- 1(n =3 0 ,P <0 0 5) ;肾上腺素 (10 μmol·L- 1)能降低 Cl- ] i,BAPTA AM (2 0 μmol·L- 1)能完全抑制 10 μmol·L- 1肾上腺素引起的Cl- ] i 变化 ,但是两者对渗透性改变引起的 Cl- ] i 变化均无影响 ;10 0nmol·L- 1PDBu可以完全抑制容积性调节的Cl-运动 ;降低 Cl- ] o 可以显著增加低渗时Cl- 的外流。结论　在A10细胞上 ,存在着容积性调节的Cl- 运动及Ca2 + 依赖性的Cl- 运动。容积性调节的Cl- 运动在低渗时激活 ,高渗时失活 ;不受胞内外Ca2 + 的影响 ;PKC的激活参与了容积性调节的Cl- 运动的调节

Effects of osmotic pressure,adrenaline,activation of PKC on Cl- movement in vascular smooth muscle cells

AIMTo investigate the modulating mechanisms of Cl - m ovement in A10 cell line. METHODSSpecific chloride fluorescent p robe-MEQ and universal imaging systems were used to observe the effects of osmo tic pressure, adrenaline, activation of PKC and extracellular chloride concentra tion on Cl - movement in A10 cell line. RESULTSResting intracel lular chloride concentration was (30 39±3 01) mmol·L -1 (n=30).Under hypotonic stimulus, intracellular chloride concentration decreased to (24 39± 2 56) mmol·L -1 from resting level(n=30,P<0 05),then increased to (34 64±3 46) mmol·L -1 (n=30,P<0 05) under hypertonic stimul us. 10 μmol·L -1 of adrenaline reduced Cl -] i, but this was comple tely abolished by 20 μmol·L -1 of BAPTA-AM. Both adrenaline and BAPTA-A M had no effects on Cl - movement under hypotonicity; 100 nmol·L -1 of PD Bu completely inhibited Cl - movement under hypotonicity. More chloride efflux was observed when extracellular chloride concentration was switched from 140 mm ol·L -1 to 0 mmol·L -1 . CONCLUSIONSVolume-regulated and Ca 2+ -dependent Cl - movements coexisted in A10 cells. The former wa s activated under hypotonicity, and inactivated under hypertonicity. Both intra -and extracellular Ca 2+ had no effects on the volume-regulated Cl - mov ement. Activation of PKC should be involved in the modulation of volume-regulat ed Cl - movement.