Endothelial cells isolated from umbilical veins (HUVEC) and from decidual biopsies collected at caesarean section delivery (DEC) from both normal (N DEC) and pre-eclamptic (PE DEC) women, were maintained in culture until passage 2, when the effect on growth of removing heparin/ECGS (endothelial cell growth supplement) from the culture medium was assessed, and the effects of heparin-free incubation and of the Ca2+ ionophore A23187 on endothelin-1, prostacyclin and prostaglandin E2 secretion over a 24 h period were examined. Cell growth slowed significantly in all three cell types in the absence of heparin/ECGS, and cell death occurred in 1/3 samples of HUVEC, 4/6 of N DEC, but 0/2 of PE DEC over 4 days. During the 24 h incubation for prostaglandin in medium without these growth factors, there was further cell death in N DEC. The addition of A23187 to this stress led to a reduction in cell number in both N DEC and HUVEC, and to a lesser extent in PE DEC. Prostaglandin and endothelin-1 levels were higher in the absence of heparin/ECGS in all cell types There was significant suppression of endothelin-1 secretion at 24 h incubation, and stimulation of prostaglandin secretion by A23187. Incubation without heparin/ECGS magnified the effect of A23187 on prostaglandin secretion, although the proportional change was similar if compared to controls without heparin/ECGS. Withdrawal of heparin/ECGS from the medium altered the balance of PGE2/PGI2 secretion by HUVEC, but not DEC. Endothelial cells require the presence of heparin/ECGS for optimum growth and viability, and N DEC are particularly dependent on these growth factors. PE DEC appear relatively 'hardy' in this regard. The addition of a further potentially toxic stimulus may result in cell death, and experiments to be conducted in limited medium must take this into account. There are both qualitative and quantitative differences in the effects of these stimuli on secretion of vasoactive substances, between decidual and umbilical vein endothelial cells.