Tomlinson P R, Wilson J W, Stewart A G
Microsurgery Research Centre, St. Vincent's Hospital, Fitzroy, Australia.
Biochem Pharmacol. 1995 Jun 16;49(12):1809-19. doi: 10.1016/0006-2952(94)00532-q.
The link between increased usage of beta-adrenoceptor agonists and worsening of asthma symptoms has raised interest in the effects of agents such as salbutamol on airway wall remodelling, and particularly airway smooth muscle proliferation. In the present study we have investigated the role of increases in intracellular cAMP in the inhibitory effect of salbutamol on airway smooth muscle proliferation. The inhibitory effects of a combination of submaximally effective concentrations of salbutamol (10 nM) and the non-selective phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX, 100 microM) on thrombin (0.3 U/mL)-induced mitogenesis in human cultured airway smooth muscle cells was greater than that for either agent alone. In addition, agents known to increase cAMP-dependent protein kinase activity including forskolin (10 microM), 8-bromoadenosine-3',5'-cyclic monophosphate (100 microM), and prostaglandin E2 (1 microM) have an inhibitory effect on thrombin (0.3 U/mL)-induced induced proliferation. Furthermore, the cAMP antagonist, 8-bromoadenosine-3',5'-cyclic monophosphorothioate, Rp-isomer (300 microM) significantly reduced the inhibitory effect of salbutamol (10 nM) on thrombin (0.3 U/mL)-induced DNA synthesis. In IBMX (100 microM)-pretreated cells, salbutamol (100 nM) increased intracellular cAMP levels via stimulation of a beta 2-adrenoceptor. Salbutamol (10 microM), at concentrations supramaximally effective for inhibition of mitogenesis, had no effect on thrombin (0.3 U/mL)-induced increases in intracellular calcium levels. Therefore, our results suggest that the previously reported inhibition of mitogen-induced proliferation in human cultured airway smooth muscle cells by the beta 2-adrenoceptor agonist, salbutamol (100 nM), is at least partly due to elevation of intracellular cAMP, while there is no effect of salbutamol on initial mitogen-induced increases in intracellular calcium.
β-肾上腺素能受体激动剂使用增加与哮喘症状恶化之间的关联引发了人们对沙丁胺醇等药物对气道壁重塑，尤其是气道平滑肌增殖影响的兴趣。在本研究中，我们调查了细胞内cAMP增加在沙丁胺醇对气道平滑肌增殖抑制作用中的作用。亚最大有效浓度的沙丁胺醇（10 nM）与非选择性磷酸二酯酶抑制剂3-异丁基-1-甲基黄嘌呤（IBMX，100 μM）联合使用，对人培养气道平滑肌细胞中凝血酶（0.3 U/mL）诱导的有丝分裂的抑制作用大于单独使用任何一种药物。此外，已知能增加cAMP依赖性蛋白激酶活性的药物，包括福斯可林（10 μM）、8-溴腺苷-3',5'-环磷酸（100 μM）和前列腺素E2（1 μM），对凝血酶（0.3 U/mL）诱导的增殖有抑制作用。此外，cAMP拮抗剂8-溴腺苷-3',5'-环磷硫酯，Rp-异构体（300 μM）显著降低了沙丁胺醇（10 nM）对凝血酶（0.3 U/mL）诱导的DNA合成的抑制作用。在经IBMX（100 μM）预处理的细胞中，沙丁胺醇（100 nM）通过刺激β2-肾上腺素能受体增加细胞内cAMP水平。沙丁胺醇（10 μM），在对有丝分裂抑制作用超最大有效浓度时，对凝血酶（0.3 U/mL）诱导的细胞内钙水平升高没有影响。因此，我们的结果表明，先前报道的β2-肾上腺素能受体激动剂沙丁胺醇（100 nM）对人培养气道平滑肌细胞中有丝分裂原诱导的增殖的抑制作用至少部分是由于细胞内cAMP升高，而沙丁胺醇对有丝分裂原最初诱导的细胞内钙增加没有影响。
