Modification by some antagonists of the shape changes of venous endothelial cells in response to inflammatory agents in vitro.

Endothelial cells lining guinea pig inferior venae cavae change shape when exposed to histamine, bradykinin, A23187 or platelet-activating factor (PAF) in vitro. Pre-treatment of the endothelium with isoprenaline or quin 2 significantly reduced the shape changes produced in response to histamine, bradykinin and A23187, but not those to PAF. Since both isoprenaline and quin 2 may reduce the concentration of cytoplasmic Ca++, the former by raising cyclic AMP (cAMP) levels and the latter by acting as a Ca++ buffer, the results provide further evidence for the involvement of Ca++ in the responses of large vein endothelial cells to inflammatory agents in vitro. The effects of pre-treating the endothelium with the histamine receptor-blockers mepyramine (H1) or cimetidine (H2), or the bradykinin receptor-blockers des-arg9[leu8] bradykinin (B1) or des-arg[Hyp3, Thi5,8,D-Phe7] bradykinin (B2) suggest that the response to histamine is both H1 and H2 receptor-mediated, while the response to bradykinin is only B2 receptor-mediated.