Endothelin: Release by and potent constrictor effect on the fetal vessels of human perfused placental lobules

Abstract

Human placental lobules were bilaterally perfused with a modified Krebs solution at constant flow rates of 5 mL min-1, and fetal inflow perfusion pressure was recorded. The effect of infusions of endothelin-1 and endothelin-3 (ET-1 and ET-3) on the perfusion pressure was assessed and compared with that for the thromboxane A2-mimetic U46619 and prostaglandin F2α (PGF2a). All substances caused significant increases in pressure, ET-1 being the most potent, followed in order by U46619, ET-3 and PGF2a. In addition, ET-like immunoreactivity was identified in the fetal effluent of placental lobules during 4 h of basal perfusion. The mean ET-1 equivalent immunoreactivity at 1 h of perfusion was 0-6 ..