VOLTAGE-DEPENDENT NA-RNA EXPRESSION IN PREGNANT MYOMETRIUM( CHANNEL MESSENGER)

The mechanisms responsible for the onset of vigorous contractile activ ity in uterine muscle at the time of parturition, reversing the obliga tory quiescence of pregnancy, remain poorly understood. We here descri be the expression in myometrium from human and from timed-pregnant rat s of an mRNA species encoding a voltage-sensitive sodium channel. The apparent concentration of this mRNA species, as measured by reverse-tr anscription polymerase chain reaction, underwent an approximately four -fold decline between mid-gestation and term. These results complement earlier reports of increased sodium current expression in mid- and la te pregnancy and further support a role for smooth muscle sodium curre nt in late pregnancy and/or labor.