石英诱导AM活化损伤中电压依赖性K^+通道的应答

Voltage Dependent K^+ Channel Responses during Activation and Damage of Alveolar Macrophage Induced by Quartz

目的研究石英颗粒对大鼠肺泡巨噬细胞(AM)电压依赖性K+通道(VDPC)的影响及意义。方法肺泡灌洗法收集SD大鼠AM,细胞浓度为5×105/ml。标准石英颗粒分为5个剂量组(0、25、50、100、200μg/ml),其中0剂量组为对照组;无定形石英颗粒100μg/ml,与AM共培养24 h后,用膜片钳记录-150～60 mV电压刺激下的细胞膜K+电流值。相同处理条件下,测定AM乳酸脱氢酶(LDH)漏出率,用MTT法测定细胞存活率。结果 AM可表达外向延迟和内向整流K+电流。石英处理24 h后可明显增加AM外向延迟K+电流(P<0.05),激活曲线左移,激活斜率减小;对内向整流K+电流影响不明显。100μg/ml无定形石英对外向延迟K+电流没有影响,但可使其激活曲线显著右移(P<0.05),激活斜率减小。随石英颗粒剂量增加,与对照组比AM LDH漏出率显著增加(P<0.05),存活率明显下降(P<0.05)。相同剂量下,无定型石英对AM的损伤程度明显小于标准石英(P<0.05)。结论石英颗粒对大鼠AM外向延迟K+通道具有激活效应,提示,该通道在石英致AM损伤坏死中充当激活信号,但与石英的生物膜毒性无关。

Objective To study the effect of quartz particulates on voltage-dependent K^＋ channels （VDPC）responses in alveolar macrophage（AM）of rats. Methods Rat AMs were collected by bronchoalveolar lavage. The cell density was adjusted to 5 × 10^6/ml. The five dosages（0,25,50,100,and 200 μg/ml）of quartz particulates and 100 μg/ml of amorphous silica were used. AMs were treated with different doses of particulates for 24 h, then the voltage dependent K^＋ currents in AMs induced by particulates were measured using patch clamp technique, meanwhile the leakage of lactate dehydrogenase（LDH）and the viability of AM were detected. Results Patch clamp studies demonstrated that outward delay and inward rectification of K^＋ currents were expressed in AMs. Quartz particulate treatment could obviously increased outward delay of K^＋ current（P〈0.05）activating the curve moving to left and reducing the slope; however, there was no effect on inward rectification of K^＋ current. Amorphous silica had no impact on outward delay of K^＋ current, but could activate the curve moving to right （P 〈 0.05）and reducing the slope. As the dosages of quartz particulates increased, the leakage of LDH from AM significantly increased compared with the control（P〈 0.05）, and the viability significantly lowered（P〈0.05）. Under the same dosages, the damage of AM induced by amorphous silica was obviously slighter than that induced by crystalline quartz. Conclusions Quartz particulate could activate the outward delay of K^＋ channel in AM of rat, which suggests that VDPC may serve as an activating signal of AM in the damage effects induced by quartz particulate; however, there is no association with cell membrane toxicity of quartz.