Influence of certain vasoactive substances on DNA synthesis in human endothelial cultures

Three-day primary human endothelial cultures from fresh umbilical veins were subjected to serotonin, l-noradrenaline, bradykinin, histamine and lymphokine at concentrations 10(-4) - 10(-9) M for 30 minutes. After removal of the test substance, the cultures were grown for a further 3 days in the presence of 3H-thymidine. DNA synthesis in the post-drug period was shown by autoradiography. Controls received identical treatment but without the drug. The test substances produced inhibition to some degree, with the exception of histamine which was stimulatory. Of the drugs considered, l-noradrenaline produced the most consistent inhibition. The statistical analysis from 399 individual observations is tabulated. Observations with histamine blocking agents mepyramine maleate for H1 sites and metiamide for H2 sites and methysergide for 5 HT receptors modified the result and confirmed the presence of receptor sites for these drugs on endothelial cells.