Changes of vascular endothelial cell shape and of membrane potential in response to the ionophore A23187.

Endothelial cells lining the thoracic inferior vena cavae of guinea-pigs were depolarised by exposure in vitro to the ionophore A23187, as judged by intracellular glass microelectrodes. There was also a simultaneous rounding up of the cell, as demonstrated by electron microscopy. Both depolarisation and change of cell shape occurred in the absence of extracellular calcium ions. Prior exposure of the endothelium to verapamil prevented both the depolarisation and the change of cell shape induced by A23187. In contrast, pretreatment with indomethacin prevented the change of cell shape but not the depolarisation induced by A23187. Possible mechanisms of action of these substances on the endothelial cell are discussed.