铁对白细胞介素-2舒血管效应的调制作用

目的 :研究微量元素铁对白细胞介素 - 2 (IL- 2 )舒血管效应的调制作用及其机理。方法 :采用离体主动脉环灌流模型 ,在苯肾上腺素 (1μmol/ L)预收缩基础上 ,测定经柠檬酸铁胺 (FAC)处理后 IL- 2对血管张力的变化 ;用分光光度法测定血管一氧化氮合酶 (NOS)活性。结果 :FAC(0 .1～ 10μmol/ L )孵育 30 min后对血管的张力无影响 ,却能浓度依赖性的抑制 IL - 2 (1～ 10 0 0 U/ ml)的舒血管效应 (P<0 .0 5～ 0 .0 1)。 IL - 2 (1、10、10 0、10 0 0 U/ ml)单独作用后的血管张力分别为加药前的 (78.4 7± 4 .31) %、(6 6 .86± 5 .5 5 ) %、(5 2 .6 2± 4 .5 1) %和 (4 2 .39± 4 .2 7) %。10 μmol/ L FAC预处理后再加 IL- 2 ,血管张力为 (89.81± 1.94 ) %、(86 .13± 3.11) %、(77.16± 5 .6 6 ) %和 (6 8.76± 5 .6 9) %。L-精氨酸 (1mmol/ L)孵育取消了 FAC对 IL- 2舒血管效应的抑制作用。IL- 2 (10 0 0 U/ ml)使 NOS的活性从 (9.86± 0 .5 4) U/ ml prot显著增高为 (2 2 .10± 1.87) U/ ml prot。FAC(10 μmol/ L)单独孵育 30 min NOS的活性为 (10 .5 9± 0 .5 9) U/ ml prot,但是 FAC预处理再加 IL - 2后 ,NOS活性显著降低为 (15 .71± 0 .89) U/ ml prot;高钙 (2 .5 mmol/ L )预处理 ,不改变 FAC对

Modulation of iron on the vasodilating effect of interleukin-2 in the isolated aortic ring

OBJECTIVE: To explore the effect and mechanism of iron on the vasodilating effect of interleukin-2 (IL-2) in the isolated aortic ring. METHODS: Isometric tension was recorded in response to drugs in organ bath. Ferric ammonium citrate (FAC) was added to the bath 30 min before phenylephrine (1 micromol/L), which was followed by IL-2 in a cumulative fashion. Spectrophotometry was used to determine the activity of nitric oxide synthase (NOS) of the thoracic aorta. RESULTS: FAC (0.1 - 10 micromol/L) alone did not affect the tension of rings,but inhibited the vasodilating effect of IL-2 (1 - 1,000 U/ml) in a dose dependent manner. IL-2(1, 10, 100, 1000 U/ml) decreased the aortic tension to (78.47+/-4.31)%, (66.86+/-5.55)%, (52.62+/-4.51)% and (42.39+/-4.27)% of pre-drug control, respectively. However, after incubation with 10 micromol/L FAC in the presence of IL-2, the aortic tension was reduced to (89.81+/-1.94)%, (86.13+/-3.11)%, (77.16+/-5.66)% and (68.76+/-5.69)% of pre-drug control, respectively. Pretreatment with L-arginine (1 mmol/L) abolished the inhibitory effect of FAC. Pretreatment with FAC attenuated the increased activity of NOS induced by IL-2 from (22.10+/-1.87)U/mg prot to (15.71+/-0.89)U/mg prot. High Ca(2+) (2.5 mmol/L) incubation did not change the inhibitory effect of FAC. Pretreatment with FAC attenuated the increased caffeine-releasable pool of Ca(2+) by IL-2. High K(+) (10 mmol/L) incubation abolished the inhibitory effect of FAC. CONCLUSION: FAC inhibits the vasodilating effect of IL-2 in the isolated aortic ring,which may be mediated by decreasing the activity of NOS. Intracellular calcium release and inward rectifier potassium channel are involved in the inhibitory effect of FAC.