Hori M, Nakaya M, Noda K, Shimizu K, Nakajyo S, Urakawa N
Department of Veterinary Pharmacology, Nippon Veterinary and Zootechnical College, Tokyo, Japan.
Jpn J Pharmacol. 1988 Sep;48(1):113-9. doi: 10.1254/jjp.48.113.
The effects of Li+ substitution for external Na+ in the medium on a 60 mN KCl (60K+)-induced contraction were compared in the ileal longitudinal smooth muscles isolated from monkey, rabbit, guinea pig and rat. Li+ substitution inhibited the 60K+-induced contraction in the ileum of all the animal species. Greater inhibitory effect was observed with the increase in external Li+ concentration and the increase in incubation period with Li+. Intracellular Li+ contents of these muscles also increased with the increase in external Li+ concentration and the incubation period. Thus, a good correlation was obtained between Li+-induced inhibition of 60K+-induced contraction and the increase in Li+ content. However, close examination revealed that the contraction in monkey and rat ileum was inhibited by much lower Li+ accumulation than that in guinea pig and rabbit ileum, suggesting the existence of species difference in the sensitivity of the ileal smooth muscle to the inhibitory effect of Li+ substitution, and a mechanism for the species differences in the inhibitory action of Li+-substitution was discussed.
比较了在培养基中用Li⁺替代外部Na⁺对从猴、兔、豚鼠和大鼠分离的回肠纵行平滑肌中60 mN KCl（60K⁺）诱导的收缩的影响。Li⁺替代抑制了所有动物物种回肠中60K⁺诱导的收缩。随着外部Li⁺浓度的增加以及Li⁺孵育时间的延长，观察到更大的抑制作用。这些肌肉的细胞内Li⁺含量也随着外部Li⁺浓度和孵育时间的增加而增加。因此，Li⁺诱导的对60K⁺诱导收缩的抑制与Li⁺含量的增加之间存在良好的相关性。然而，仔细检查发现，猴和大鼠回肠中的收缩受到的Li⁺积累抑制比豚鼠和兔回肠中的要低得多，这表明回肠平滑肌对Li⁺替代抑制作用的敏感性存在物种差异，并讨论了Li⁺替代抑制作用中物种差异的机制。
