Calcium and depolarization-dependent effect of pregnenolone derivatives on uterine smooth muscle |
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| Institution: | 1. Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 532 10 Pardubice, Czech Republic;2. Department of Biological and Biochemical Science, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 532 10 Pardubice, Czech Republic;3. Department of Medical Biochemistry, Faculty of Medicine in Hradec Králové, Charles University in Prague, ?imkova 870, 500 38 Hradec Králové, Czech Republic;4. Institute of Chemistry and Technology of Macromolecular Materials, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 532 10 Pardubice, Czech Republic;5. Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, T?ebe?ská 1575, 500 01 Hradec Králové, Czech Republic;6. Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 532 10 Pardubice, Czech Republic;1. Department of Surgery, Kansai Medical University, Osaka, Japan;2. Department of Pathology and Clinical Laboratory, Kansai Medical University, Osaka, Japan;1. Department of Otorhinolaryngology, Head and Neck Surgery, AMEOS Klinikum Haldensleben, Germany;2. Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center of the Johannes Gutenberg University Mainz, Germany;1. MB BCh BAO MCh Connolly Hospital, Blanchardstown, Dublin, Ireland;2. FRCSI Connolly Hospital, Blanchardstown, Dublin, Ireland |
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| Abstract: | - 1.1. The effects of several gestagens (pregnenolone 1 to 30 μm], 20α-hydroxypregnenolone 1 to 30 μM]), and 20β-hydroxypregnenolone 1 to 30 μm]) on rat uterine contraction induced by KC1 (60 mM) and CaCl2 (30 μM to 6 mM) have been assayed.
- 2.2. The three drugs relaxed the tonic contraction induced by KCI in a concentration-dependent way. The respective EC50 values were: 27.6±1.58 μM (pregnenolone), 4.1±0.12 μM (20α-hydroxypregnenolone), and 11.2±1.04 μM (20β-hydroxypregnenolone). CaCl2 (1 to 10 mM) totally counteracted the relaxing effect of pregnenolone but only partially compared to that of 20α- or 20β-hydroxy-pregnenolone.
- 3.3. CaC12 (30 μM to 6 mM) produced concentration-dependent contraction of rat uterus in medium lacking calcium plus 30, 60, or 90 mM of KC1. The EC50 values of CaCl2 were: 0.38±0.072, 0.183±0.015, and 0.183±0.015 μM in a medium with 30, 60, or 90 mM of KCI, respectively.
- 4.4. Pregnenolone (10 μM) did not significantly modify the EC50 of CaC12 in a medium with 30, 60, or 90 mM of KCI. However, 20β-hydroxypregnenolone (10 μM) antagonized, in a noncompetitive manner, the concentration-response curve to CaC12.
- 5.5. 20α-Hydroxypregnenolone (4 μM) antagonized the concentration-response curve to CaCl2 in a competitive manner. This antagonism was directly related to the concentration of KCI in the medium.
- 6.6. Our results suggest a different calcium antagonist effect of the three gestagens assayed.
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