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Properties of intracellular calcium stores in pregnant rat myometrium
Author(s) -
Kanmura Y.,
Missiaen L.,
Casteels R.
Publication year - 1988
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1988.tb16575.x
Subject(s) - contraction (grammar) , myometrium , muscle contraction , calcium , uterine contraction , chemistry , medicine , endocrinology , inositol , biophysics , inositol trisphosphate , intracellular , biology , biochemistry , uterus , receptor
1 The properties of the Ca 2+ stores in myometrium of 21‐day pregnant rats were studied by recording the contractile responses of saponin‐treated skinned muscles. 2 After accumulation of Ca 2+ into the stores in the presence of 5mM NaN 3 , inositol 1,4,5‐trisphosphate (InsP 3 ) at concentrations exceeding 3 μ M produced a contraction. The amplitude of this contraction was maximal at about 20 μ M . A second application of 20 μ M InsP 3 produced a smaller contraction than the first one. However after reloading the stores with Ca 2+ , 20 μ M InsP 3 produced a contraction of the same amplitude as the initial one. 3 After application of 20 μ M InsP 3 , 1 μ M A23187 still evoked a large contraction. If A23187 was applied first, the subsequent application of InsP 3 or A23187 no longer induced a contraction, even after Ca 2+ loading. 4 Guanosine triphosphate (GTP) or arachidonic acid, both 100 μ M neither evoked a contraction nor enhanced the subsequent contraction elicited by 20 μ M InsP 3 . 5 Caffeine 25 mM did not induce a contraction nor did it affect the contraction elicited by 20 μ M InsP 3 . 6 The results indicate that in pregnant rat myometrium InsP 3 releases Ca 2+ from intracellular stores as has been proposed in vascular smooth muscles.