Murakami K, Karaki H, Nakagawa H, Urakawa N
Naunyn Schmiedebergs Arch Pharmacol. 1984 Jan;325(1):80-4. doi: 10.1007/BF00507058.
The effects of X537A (Lasalocid) on contractions induced in vascular and intestinal smooth muscles were examined. High K-induced sustained contractions were inhibited by X537A with an IC50 of 2.8 X 10(-6) M in rabbit aorta and 8.8 X 10(-8) M in guinea-pig Taenia coli. Changing the Ca concentration in the medium did not modify the effect of X537A. X537A also inhibited the noradrenaline-induced contraction in aorta (IC50 = 7.0 X 10(-8) M). In a solution without added glucose, the inhibitory effect of X537A on the K-induced contraction in aorta was augmented (IC50 = 1.5 X 10(-8) M). Under hypoxic conditions, the inhibitory effects of X537A on the noradrenaline-induced contractions in aorta and on the K-induced contraction in T. coli were decreased (IC50 greater than 10(-5) M and 3.2 X 10(-6) M, respectively). X537A inhibited the K-induced increase in cellular 45Ca content in aorta measured by a modified lanthanum method. However, the IC50 for 45Ca uptake (6.6 X 10(-7) M) was lower than that for K-induced contraction. In both tissues, X537A decreased the ATP content. Oxygen consumption of rat liver mitochondria was inhibited by X537A. From these results, it is concluded that the inhibitory effect of X537A on the noradrenaline-induced contraction in aorta and the K-induced contraction in T. coli, but not the K-induced contractions in aorta, may be due to the inhibition of aerobic metabolism.
研究了X537A（拉沙洛西）对血管和平滑肌收缩的影响。在兔主动脉中，X537A抑制高钾诱导的持续性收缩，IC50为2.8×10⁻⁶M；在豚鼠结肠带中，IC50为8.8×10⁻⁸M。改变培养基中的钙浓度不会改变X537A的作用。X537A还抑制主动脉中去甲肾上腺素诱导的收缩（IC50 = 7.0×10⁻⁸M）。在不添加葡萄糖的溶液中，X537A对主动脉中钾诱导收缩的抑制作用增强（IC50 = 1.5×10⁻⁸M）。在缺氧条件下，X537A对主动脉中去甲肾上腺素诱导收缩和结肠带中钾诱导收缩的抑制作用减弱（IC50分别大于10⁻⁵M和3.2×10⁻⁶M）。X537A抑制用改良镧法测定的主动脉中钾诱导的细胞45Ca含量增加。然而，45Ca摄取的IC50（6.6×10⁻⁷M）低于钾诱导收缩的IC50。在两种组织中，X537A均降低ATP含量。X537A抑制大鼠肝线粒体的氧消耗。从这些结果得出结论，X537A对主动脉中去甲肾上腺素诱导收缩和结肠带中钾诱导收缩的抑制作用，而非主动脉中钾诱导的收缩，可能是由于有氧代谢的抑制。
