Kabir Syeda M, Mukherjee Shyamali, Rajaratnam Veera, Smith Milton G, Das Salil K
Department of Cancer Biology, Meharry Medical College, 1005 David Todd Blvd., Nashville, TN 37208, USA.
J Biochem Mol Toxicol. 2009 Jan-Feb;23(1):59-70. doi: 10.1002/jbt.20265.
2-Choloroethyl Ethyl Sulfide (CEES) exposure causes inflammatory lung diseases, including acute respiratory distress syndrome (ARDS) and pulmonary fibrosis. This may be associated with oxidative stress, which has been implicated in the desensitization of beta-adrenergic receptors (beta-ARs). The objective of this study was to investigate whether lung injury induced by intratracheal CEES exposure (2 mg/kg body weight) causes desensitization of beta-ARs. The animals were sacrificed after 7 days and lungs were removed. Lung injury was established by measuring the leakage of iodinated-bovine serum albumin ([(125)I]-BSA) into lung tissue. Receptor-binding characteristics were determined by measuring the binding of [(3)H] dihydroalprenolol ([(3)H] DHA) (0.5-24 nM) to membrane fraction in the presence and absence of DLDL-propranolol (10 micro M). Both high- and low-affinity beta-ARs were identified in the lung. Binding capacity was significantly higher in low-affinity site in both control and experimental groups. Although CEES exposure did not change K(D) and B(max) at the high-affinity site, it significantly decreased both K(D) and B(max) at low affinity sites. A 20% decrease in beta(2)-AR mRNA level and a 60% decrease in membrane protein levels were observed in the experimental group. Furthermore, there was significantly less stimulation of adenylate cyclase activity by both cholera toxin and isoproterenol in the experimental group in comparison to the control group. Treatment of lungs with 3-isobutyl-1-methylxanthine (IBMX), an inhibitor of phosphodiesterase (PDE) could not abolish the difference between the control group and the experimental group on the stimulation of the adenylate cyclase activity. Thus, our study indicates that CEES-induced lung injury is associated with desensitization of beta(2)-AR.
2-氯乙基乙基硫醚（CEES）暴露会引发炎症性肺部疾病，包括急性呼吸窘迫综合征（ARDS）和肺纤维化。这可能与氧化应激有关，氧化应激已被认为与β-肾上腺素能受体（β-ARs）的脱敏有关。本研究的目的是调查气管内注入CEES（2毫克/千克体重）所诱导的肺损伤是否会导致β-ARs脱敏。7天后处死动物并取出肺脏。通过测量碘化牛血清白蛋白（[(125)I]-BSA）向肺组织的渗漏来确定肺损伤。通过在存在和不存在DLDL-普萘洛尔（10微摩尔）的情况下测量[(3)H]二氢阿普洛尔（[(3)H] DHA）（0.5 - 24纳摩尔）与膜组分的结合来确定受体结合特性。在肺中鉴定出了高亲和力和低亲和力的β-ARs。对照组和实验组中低亲和力位点的结合能力均显著更高。尽管CEES暴露并未改变高亲和力位点的解离常数（K(D)）和最大结合容量（B(max)），但它显著降低了低亲和力位点的K(D)和B(max)。在实验组中观察到β(2)-AR信使核糖核酸（mRNA）水平下降20%，膜蛋白水平下降60%。此外，与对照组相比，实验组中霍乱毒素和异丙肾上腺素对腺苷酸环化酶活性的刺激明显减少。用磷酸二酯酶（PDE）抑制剂3-异丁基-1-甲基黄嘌呤（IBMX）处理肺脏并不能消除对照组和实验组在腺苷酸环化酶活性刺激方面的差异。因此，我们的研究表明，CEES诱导的肺损伤与β(2)-AR脱敏有关。
