Intracellular $Ca^{2+}$ Movement in Contraction Induced by Carbachol and Oxytocin in Rat Myometrium

자궁평활근의 Carbachol 및 Oxytocin 수축에 있어서의 세포내 $Ca^{2+}$ 동원

  • Kim, Bo-Kyung (Department of Veterinary Medicine, Kon-Kuk University) ;
  • Chung, Dong-Su (Department of Veterinary Medicine, Kon-Kuk University) ;
  • Kim, Yoon-Sun (Department of Veterinary Medicine, Kon-Kuk University) ;
  • Lee, Yoon-Ho (Department of Veterinary Medicine, Kon-Kuk University) ;
  • Yong, Jun-Hwan (Department of Veterinary Medicine, Kon-Kuk University) ;
  • Lee, Won-Chang (Department of Veterinary Medicine, Kon-Kuk University) ;
  • Ozaki, Hiroshi (Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo) ;
  • Karaki, Hideaki (Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo) ;
  • Lee, Sang-Mog (Department of Veterinary Medicine, Kon-Kuk University)
  • Published : 1996.09.30

Abstract

The properties of cytosolic $Ca^{2+}$ level$([Ca^{2+}]_i)$ movement of high KCl, carbachol and oxytocin were examined with myometrium isolated from non-pregnant rat(estrus cycle). High concentration of KCl$({\leq}23.3mM)$ induced rhythmic increases in $[Ca^{2+}]_i$ and muscle contraction. However, sustained $[Ca^{2+}]_i$ and contracion were obtained at higher KCl concentration $({\geq}30.3mM)$ The rhythmic and sustained contraction closely associated with changes in $[Ca^{2+}]_i$ induced by high KCl. Carbachol $(3{\sim}30{\mu}M$ generated rhythmic increases with tonic component in $[Ca^{2+}]_i$ and muscle contraction. Myometrial contraction stimulated by carbachol was also closely correlated with change in $[Ca^{2+}]_i$. And the $[Ca^{2+}]_i/contraction$ relationships were similar when muscle strips were stimulated by high KCl and carbachol. Maximal concentration of carbachol $(10{\mu}M)$ and oxytocin(100 nM) increased $[Ca^{2+}]_i$ and contraction which were slightly greater than that of high KCl in non-pregnant myometrium, respectively. However, the $[Ca^{2+}]_i$ and contraction were strongly inhibited by verapamil $(10{\mu}M)$, a 1-type $Ca^{2+}$ channel blocker, as in the case of high KCl. Additionally, although carbachol further increased $[Ca^{2+}]_i$ and contraction induced by high KCl, these changes also strongly inhibited by application of verapamil. These results suggest that uterotonic agents, carbachol and oxytocin, induced contraction by increase in $[Ca^{2+}]_i$ through $Ca^{2+}$ influx than by a regulation of $Ca^{2+}-sensitization$ in non-pregnant myometrium.

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