REGULATION OF THE SODIUM-PUMP IN PREGNANCY-RELATED TISSUES IN PREECLAMPSIA

OBJECTIVE: This study examined the expression of the three alpha-isofo rms of the sodium pump in preeclampsia. Reductions in sodium pump numb er and activity in smooth muscle may underlie hypertension in preeclam psia. STUDY DESIGN: Northern and Western analyses were used to determi ne whether sodium pump alpha-isoform regulation in myometrium, placent a, and umbilical artery of women with preeclampsia differed from those with normotensive pregnancies. RESULTS: Levels of alpha 1 and alpha 3 messenger ribonucleic acid were reduced in myometrium of women with p reeclampsia compared with normotensive pregnancies, as was alpha 2 mes senger ribonucleic acid in preeclamptic placenta. Protein expression o f the alpha-isoforms was unaltered in placenta and umbilical artery fr om women with preeclampsia versus those with normotensive pregnancies, but myometrial alpha 2 protein levels were reduced significantly in w omen with preeclampsia. Moreover, myometrial alpha 1 protein expressio n was undetectable. CONCLUSIONS: Reduced smooth muscle sodium pump exp ression in preeclampsia may raise cell sodium, increase presser sensit ivity, or increase tone directly, which may contribute to hypertension in preeclampsia.