ENDOTHELIN-1 AND BIG ENDOTHELIN-1 INCREASE IN HUMAN ENDOMETRIUM DURING MENSTRUATION

OBJECTIVES: Although the physiologic and pathologic roles of endotheli n-1 in reproduction have been investigated, little is known about huma n uterine tissue levels. We studied the levels of immunoreactive endot helin-1 and immunoreactive big endothelin-1 in human endometrium and m yometrium during each menstrual phase. STUDY DESIGN: Materials were ob tained at hysterectomy (endometrium, n = 33; myometrium, n = 27). We m easured immunoreactive endothelin-l and immunoreactive big endothelin- 1 by radioimmunoassay and performed an immunohistochemical study of th e tissue. Data were analyzed by the Mann-Whitney U test. RESULTS: We d etected larger amounts of immunoreactive endothelin-1 and immunoreacti ve big endothelin-1 in the endometrium than in the myometrium througho ut the menstrual, proliferative, and secretory phases. Endometrial imm unoreactive endothelin-1 and immunoreactive endothelin-1 were signific antly increased in the menstrual phase (endothelin-1 68.8 +/- 23.3 pg/ mg protein, n = 5, p < 0.005; big endothelin-1 45.2 +/- 5.7 pg/mg prot ein, n = 5, p < 0.003) compared with the other phases (endothelin-1 30 .7 +/- 9.5 and 30.5 +/- 14.0 pg/mg protein; big endothelin-1 19.9 +/- 6.7 and 24.1 +/- 7.4 pg/mg protein). Immunohistochemistry demonstrated that the endometrial stromal cells were positive for antiendothelin m onoclonal antibody only in the premenstrual and menstrual phases. CONC LUSION: Levels of immunoreactive endothelin-1 and immunoreactive big e ndothelin-1 are different in each type of uterine tissue and in each p hase of the menstrual cycle. These changes may indicate some role of e ndothelin-1 in menstruation