ENDOTHELIN RECEPTOR-TYPE-A AND RECEPTOR-TYPE-B GENE-EXPRESSION IN HUMAN NONPREGNANT, TERM PREGNANT, AND PREECLAMPTIC UTERUS

OBJECTIVE: The aim of this study was to quantify the gene expression o f ET(A) and ET(B) receptors within the different uterine segments of n onpregnant, normal pregnant, and preeclamptic women. STUDY DESIGN: Bio psy samples from the cervix, isthmus, and corpus uteri were obtained f rom eight nonpregnant, nine term pregnant, and seven preeclamptic wome n. The concentration of ET(A) and ET(B) receptor messenger ribonucleic acid were determined by a solution hybridization technique with compl ementary ribonucleic acid probes. Results are presented in counts per minute per microgram of total nucleic acid as mean +/- SEM. RESULTS: T he expression of messenger ribonucleic acid encoding the ET(A) recepto r was generally higher in the upper than in the lower uterine segment in nonpregnant, normal pregnant, and preeclamptic myometrium, whereas the opposite pattern was seen with regard to ET(B). During normal preg nancy the concentrations of ET(A) receptor messenger ribonucleic acid in the corpus and ET(B) receptor messenger ribonucleic acid in the ist hmus were significantly elevated compared with those in nonpregnant wo men. This enhanced gene expression was, however, not observed in the p reeclamptic group. CONCLUSION: Our finding of segmentally differentiat ed endothelin receptor gene expression is compatible with a role for e ndothelin-l in stimulating uterine contractions through ET(A) receptor s during spontaneous labor and suggests a relaxing effect of the ET(B) receptor on the myometrium.