High affinity Ca-binding to smooth muscle plasma membrane: Inhibition by cations Academic Article uri icon

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abstract

  • The effects of Mg2+, Na+ and K+ on the pH-dependent high affinity passive Ca-binding to sarcolemmal enriched membrane fractions from the smooth muscles of rat myometrium and gastric fundus were examined at 1 uM Ca2+-concentration. For the myometrial plasma membranes, these ions inhibited the passive Ca-binding with the following IC50 values: Mg2+: 1.75 mM; Na+: 19 mM; K+: 233 mM. Similarly, for the gastric fundus membranes, the IC50 values were Mg2+:1.6 mM, Na+:46 mM and K+:67 mM.

publication date

  • June 1986