| Project/Area Number |
08671863
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Obstetrics and gynecology
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| Research Institution | YAMAGATA UNIVERSITY |
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Principal Investigator |
TEZUKA Naohiro YAMAGATA UNIV.SCHOOL OF MEDI.ASSISTANT PROF., 医学部, 講師 (60261690)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1996: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | Myometrium / Ion channel / Molecular biology |
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| Research Abstract |
Extracellular Ca^<2+> is required for myometrial cells to contract forcefully. Ca^<2+> enters muscle cells mainly through voltage-dependent Ca^<2+> channels (VDCCs) that open in response to action potentials. The synthesis of myometrial VDCCs may change during pregnancy to alter excitation-contraction coupling. We investigated the levels of L-type VDCC alpha1-subunit mRNA in rat and human myometrium to determine whether alterations are associated with term or preterm labor. RNA isolated from myometrial tissues was analyzed by reverse transcription-PCR using specific primers designed according to the published sequence. From pregnant rat myometrium, two distinct PCR products were obtained : one of the expected size at 372 base pairs (bp) and a smaller at 339bp. The two products followed the same trend throughout pregnancy. VDCC mRNA levels increased gradually to 6.9-fold just prior to labor on day 22, but decreased during labor. Similarly ZK98.299 treatment on day 17 caused a statistically significant increase after 8 hours then a decrease during preterm labor at 24 hours. There was no significant increase in animals treated with progesterone from day 19 to day 22. From human myometrium, two PCR products were also obtained. VDCC mRNA levels in the term no labor group were about 4-fold higher than those in the term with labor. We conclude that mRNA levels increase prior to term and preterm labor but decline during periods when VDCCs are likely at their peaks. Progesterone withdrawal or blockade appears to be responsible for regulating the expression of VDCC in preparation for the myometrium to contract.
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