Concentrations of Endothelin-1 in Human Amniotic Fluid at Various Stages of Pregnancy

Secretion of Endothelin by Avascular Amnion Tissue: Possible Roles in H Pregnancy

“…On the other hand, others reported that the ET-1-LI level in the amniotic fluid obtained after the onset of labor was similar to that found at the time of elective cesarean section before the onset of labor [8,28]. Recently, Casey et al [35] reported an additional finding that may help explain some of these contradictions; they found that the amniotic fluid concentration of ET-1-LI was higher below the fetal head than in the upper compartment of the amniotic cavity.…”

“…peptides originally isolated from the culture medium of porcine aortic endothelial cells [1].Three distinct ET-related genes are found in the human genomic library,and the corresponding peptides are designated as ET-1,ET-2 and ET-3 [2].Prepro-ET-1 mRNA is constitutively expressed by cultured endothelial cells.ET-1 is also secreted from various non-vascular tissues including reproductive organs such as mammary tissue [3],decidual stromal cells of the maternal basal plate of the placenta [4],placental syncytiotrophoblasts and extravillous cytotrophoblasts [5]and amnion tissue [6][7][8][9].ET-2 and ET-3 are expressed in other tissues,such as the brain,kidney,adrenal,intestine and placenta [10][11][12].…”

“…ET exerts biological activity through specific receptors.Two distinct cDNAs for ET receptors were identified.One of these,which is ET-1 selective,is expressed in vascular smooth muscle cells(ET-A receptor;ET-AR) [13],and the other,which is nonisopeptide-selective,is expressed in vascular endothelial cells(ET-B receptor;ET-BR) [14].The order of affinity for ET-AR is ET-1>ET-2•âET-3, with the affinity of ET-1 or ET-2 being approximately two orders of magnitude higher than that of ET-3 [13,15].ET-BR has equipotent affinity for all three isopeptides [16].Thus,ET-1 and ET-2 have high affinity for both ET-AR and ET-BR,but ET-3 Concentrations and molecular forms of ET-1-like immunoreactivity in human amniotic fluid A number of investigators [6][7][8]28, 29] report ET-1-like immunoreactivity (ET-1-LI) in the human amniotic fluid at a concentration several times higher than that found in maternal or fetal plasma [28,[30][31][32]. Figure 1 compares ET-1-LI levels in the amniotic fluid at various gestational ages with those in neonatal first urine, maternal plasma and umbilical venous plasma.…”

“…ET-1-LI in amniotic fluid increases as gestation advances. Human amniotic fluid in the midtrimester contains big ET-1 and a larger form (6 kDa) of ET-1-LI [8,28]. The concentration of this larger form of ET decreases towards term, and the mature form of ET-1 becomes the major constituent of ET-1-LI in the amniotic fluid at term [8].…”

“…Human amniotic fluid in the midtrimester contains big ET-1 and a larger form (6 kDa) of ET-1-LI [8,28]. The concentration of this larger form of ET decreases towards term, and the mature form of ET-1 becomes the major constituent of ET-1-LI in the amniotic fluid at term [8]. ET-1-LI is also found in the first neonatal urine; however, its concentration is much lower than that in the amniotic fluid at term [8,28] Relation between the amniotic fluid ET-1 concentration and labor…”