S-Space College of Medicine/School of Medicine (의과대학/대학원) Dept. of Medicine (의학과) The Seoul Journal of Medicine The Seoul Journal of Medicine Vol. 20 No.4 (1979)
칼슘이 흰쥐 자궁근 수축에 미치는 영향황 : Effect of Ca" on the contractility of isolated uterine muscle activated by oxytocin and potassium-hypopolarization in estrous rat
- Issue Date
- 서울대학교 의과대학
- Seoul J Med, Vol.20 No.3, pp. 253-260
- The influeuces of Ca" upon the contractility of
isolated uterine muscle were studied. Longitudinal
muscle strips were prepared from the rat uteri in
estrous stage, and the contractions of these strip.
were promoted by oxytocin treatment or potassiuminduced
hypopolarization. AU experiments were performed
in Tris-buffered Tyrode solution which was
aerated with 100% 0, and kept at 35'C.
The results obtained were as follows:
1. Oxytocin (10- 3 LU.lt) promoted smaU, irregular
spontaneous contractions to regular, rhythmic ones
in an all-or-none manner. As the concentration increased
to 10 LU., both frequency of contraction and
amplitude of peak tension were increased.
2. In the activated strips by oxytocin (1 LU.),
the area of contraction curve increased dose-dependently
in the range of 4~16mM Ca" while the frequency
of contraction decreased. and the amplitude of
peak tension was not altered significantly within this
range. In Ca't-free media, however, contraction was
not developed even under the influence of higher
concentration of oxytocin (10 LU.).
3. Potassium promoted the contractions of uterine
strips in proportion to an increase of K+ concentration
in media. Spontaneous activity increased dose-dependently
to 20mM K+, but contracture appeared above
the concentration of 30mM K+.
4. In the hypopolarized strips by 20mM potassium,
all parameters were increased dose-dependently in the
range of 4~32mM Ca": area of contraction curve,
frequency of contraction. and amplitude of peak
tension increased all together.The above results suggest that external calcium
ion is essential for spontaneous uterine contraction
and oxytocin action to uterine muscle, and it parti-
cipates directly in action potential as an inward
current in potassium-hypopolarized state.