Abdullah N A, Hirata M, Matsumoto K, Aizawa H, Inoue R, Hamano S, Ikeda S, Xie Z, Hara N, Ito Y
Department of Pharmacology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Am J Physiol. 1994 May;266(5 Pt 1):L528-35. doi: 10.1152/ajplung.1994.266.5.L528.
We investigated the effects of fetal bovine serum (FBS) on the resting membrane potential and muscle tone of canine airway smooth muscles using tension recording and microelectrode methods. At concentrations > 0.1%, FBS induced a sustained increase in muscle tone. At concentrations > 1%, FBS depolarized the resting membrane potential of dog trachea in a dose-dependent manner. When FBS was dialyzed, it failed to induce a sustained increase in muscle tone or to depolarize the membrane, indicating that FBS contained factor(s) that induced contraction of dog airway smooth muscles. When FBS was dialyzed against distilled water, the outer solution which was freeze dried and then reconstituted (> 1% in original vol) induced a sustained increase in muscle tone, indicating that FBS contained dialyzable factor(s) that increased muscle tone and depolarized the resting membrane potential of dog airway smooth muscles. Methysergide (10(-6) M) or cyproheptadine (10(-6) M), nonspecific antagonists to serotonin receptors, 5-hydroxytryptamines (5-HT1 and 5-HT2), markedly reduced the FBS-induced increase in the muscle tone to approximately 20% of the original value but did not abolish the response. On the other hand, methysergide (10(-6) M) completely suppressed the increase in the muscle tone evoked by peak fractions obtained by application of the dialysate of FBS or 5-HT to a C18 reverse-phase column, indicating the peak fractions contained only 5-HT. These observations indicate that FBS contained 5-HT and an unknown factor(s) responsible for increase in the muscle tone of the airway smooth muscle induced by FBS.
我们使用张力记录和微电极方法研究了胎牛血清（FBS）对犬气道平滑肌静息膜电位和肌张力的影响。当浓度>0.1%时，FBS可引起肌张力持续升高。当浓度>1%时，FBS可使犬气管的静息膜电位呈剂量依赖性去极化。当FBS经过透析后，它无法引起肌张力的持续升高或使膜去极化，这表明FBS中含有诱导犬气道平滑肌收缩的因子。当FBS用蒸馏水透析时，将透析后的外部溶液冻干然后重新配制（体积为原来的>1%）可引起肌张力持续升高，这表明FBS中含有可透析的因子，这些因子可增加肌张力并使犬气道平滑肌的静息膜电位去极化。5-羟色胺（5-HT1和5-HT2）的非特异性拮抗剂麦角新碱（10⁻⁶ M）或赛庚啶（10⁻⁶ M）可将FBS诱导的肌张力升高显著降低至约为原始值的20%，但并未消除该反应。另一方面，麦角新碱（10⁻⁶ M）完全抑制了将FBS或5-HT的透析液应用于C18反相柱所获得的峰组分诱发的肌张力升高，这表明峰组分中仅含有5-HT。这些观察结果表明，FBS中含有5-HT以及一种未知因子，该未知因子导致了FBS诱导的气道平滑肌肌张力升高。
