Endothelin receptor type A and B gene expression in human nonpregnant, term pregnant, and preeclamptic uterus

Abstract

OBJECTIVE: The aim of this study was to quantify the gene expression of ET A and ET B receptors within the different uterine segments of nonpregnant, normal pregnant, and preeclamptic women. STUDY DESIGN: Biopsy samples from the cervix, isthmus, and corpus uteri were obtained from eight nonpregnant, nine term pregnant, and seven preeclamptic women. The concentration of ET A and ET B receptor messenger ribonucleic acid were determined by a solution hybridization technique with complementary ribonucleic acid probes. Results are presented in counts per minute per microgram of total nucleic acid as mean ± SEM. RESULTS: The expression of messenger ribonucleic acid encoding the ET A receptor 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 pregnancy the concentrations of ET A receptor messenger ribonucleic acid in the corpus and ET B receptor messenger ribonucleic acid in the isthmus were significantly elevated compared with those in nonpregnant women. This enhanced gene expression was, however, not observed in the preeclamptic group. CONCLUSION: Our finding of segmentally differentiated endothelin receptor gene expression is compatible with a role for endothelin-1 in stimulating uterine contractions through ET A receptors during spontaneous labor and suggests a relaxing effect of the ET B receptor on the myometrium. (Am J Obstet Gynecol 1996;175:1295-300.)