Characterization and actions of human umbilical endothelium derived relaxing factor.

1. A bioassay cascade superfusion technique was utilized to study the properties of endothelium derived relaxing factor (EDRF) from human umbilical vein (HUV) and compare its actions on umbilical, chorionic plate and bovine pulmonary arterial strips. 2. Histamine (1 microM), bradykinin (1 microM) and A-23187 (0.3 microM, 1 microM) but not acetylcholine (1 microM) released EDRF. 3. The non-innervated human foetoplacental vessels, i.e., umbilical and chorionic plate arteries, do relax to EDRF by a guanosine 3':5'-cyclic monophosphate (cyclic GMP)-mediated mechanism. 4. The sensitivity of the human umbilical arterial strips to EDRF was less than that of the chronic plate arterial strips. Bovine pulmonary arterial strips were the most sensitive to the relaxant actions of human umbilical EDRF.