Expression of nitric oxide synthase isoforms and detection of nitric oxide in rat placenta
2009
Ikeda, Y.(Azabu Univ., Sagamihara, Kanagawa (Japan). School of Veterinary Medicine) | Mori, C. | Takizawa, T.
Nitric oxide (NO) production in the rat placenta (pars fetalis placentae and decidua basalis) was monitored and quantified by electron paramagnetic resonance (EPR) spectroscopy using an iron complex with N-(dithiocarboxy) sarcosine (Fe-DTCS) as a NO trapping reagent. The expression of nitric oxide synthase (NOS) isoforms was also examined by quantitative reverse transcriptase-mediated polymerase chain reaction (RT-PCR) analysis. The EPR spectrum of the placenta with Fe-DTCS trapping showed a triplet signal (g = 2.038) derived from an NO-Fe-DTCS complex. The heights of the NO-Fe-DTCS (a) and MnO (b) signals were simultaneously measured to calculate the ratio (a/b) of these signal heights used for the quantification of the NO production level. Although, the ratio of the signal heights of NO-Fe-DTCS and MnO did not vary significantly with gestational stage in the fetal placenta, the ratio was markedly decreased in the maternal placenta during the last few days of gestation. At the gestational stages examined, the level of NOS 2 (iNOS) mRNA expression was significantly higher than that of NOS 3 (eNOS) mRNA expression at any given stage in the fetal placenta, and the production pattern of NO was in good accordance with the expression pattern of NOS 2 in the maternal placenta. These results suggest that NOS 2 is the predominant producer of NO in the placenta and that NOS 2-generated NO plays significant roles in the maintenance of placental functions immediately before birth.
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