Endoh M, Nagai M, Nakase Y
Department of Microbiology, School of Pharmaceutical Sciences, Kitasato University, Tokyo.
Microbiol Immunol. 1988;32(8):755-67. doi: 10.1111/j.1348-0421.1988.tb01437.x.
Using both vascular smooth muscle strips (VSMS) and cultured cells (VSMC) from aortas of pigs, the contractile action of Bordetella heat-labile toxin (HLT) purified from B. parapertussis was studied in an attempt to elucidate the mechanisms of its action. HLT induced contractions in VSMC in parallel with the increase of Ca2+-influx. The HLT-induced Ca2+-influx and contraction were not influenced by verapamil or diltiazem, though a certain extension of the lag period was seen. The contractile action of HLT on VSMS and VSMC was not influenced either by diltiazem or quinacrine; that on VSMC was not influenced by prednisolone, indomethacin, aspirin, CV-3988, FPL-55712, ruthenium red, or TEAC. On VSMS, prednisolone caused the extension of lag period following HLT exposure. The action of HLT on VSMS was inhibited by TMB-8, whereas that on VSMC was not though the extension of lag period was seen. The HLT-induced contraction in both VSMS and VSMC was completely inhibited by H-7. The contraction in VSMS, but not in VSMC, was inhibited by H-8. HLT did not induce specific activation of the protein kinases in VSMC. The addition of cGMP or cAMP brought about relaxation in the HLT-exposed VSMS contracting in maximum. HLT caused a significant increase in permeability of VSMC membrane to trypan blue, accompanied with contraction. Both HLT-induced contraction and increase in permeability were inhibited by dextran of M.W. 8,000, but not of M.W. 5,000. These results suggested that HLT acted on vascular smooth muscle cells by damaging the membrane permeability, but not by disturbing the known cascades or systems for physiological contractions, resulting in the increase in Ca2+-influx and then contractions.
利用猪主动脉的血管平滑肌条（VSMS）和培养细胞（VSMC），研究了从副百日咳博德特氏菌中纯化的百日咳热不稳定毒素（HLT）的收缩作用，以阐明其作用机制。HLT诱导VSMC收缩，同时伴随着Ca2+内流的增加。尽管观察到滞后时间有一定延长，但HLT诱导的Ca2+内流和收缩不受维拉帕米或地尔硫䓬的影响。HLT对VSMS和VSMC的收缩作用既不受地尔硫䓬也不受喹吖因的影响；对VSMC的收缩作用不受泼尼松龙、吲哚美辛、阿司匹林、CV-3988、FPL-55712、钌红或TEAC的影响。在VSMS上，泼尼松龙会导致HLT作用后滞后时间延长。HLT对VSMS的作用被TMB-8抑制，而对VSMC的作用虽观察到滞后时间延长但未被抑制。HLT在VSMS和VSMC中诱导的收缩均被H-7完全抑制。VSMS中的收缩被H-8抑制，但VSMC中的收缩未被抑制。HLT未诱导VSMC中蛋白激酶的特异性激活。添加cGMP或cAMP可使最大收缩的HLT作用后的VSMS松弛。HLT导致VSMC膜对台盼蓝的通透性显著增加，并伴有收缩。HLT诱导的收缩和通透性增加均被分子量为8000的葡聚糖抑制，但未被分子量为5000的葡聚糖抑制。这些结果表明，HLT通过破坏膜通透性作用于血管平滑肌细胞，而不是通过干扰已知的生理收缩级联反应或系统，导致Ca2+内流增加进而引起收缩。
