Protection by Iloprost (stable analogue of prostacyclin) of endothelial damage due to chronic vasospasm in dogs: an electron microscope study.

The resolution of cerebral vasospasm and protection of endothelial damage by Iloprost was evaluated with multicisternal injections. Sixteen adult mongrel dogs (18-20 kg) were assigned to one of three experimental groups. All animals received a total amount of 15 ml fresh unheparinized arterial blood via three injections into the cisterna magna. Selective vertebral angiography was performed on day 0 and subsequently blood injections were performed on the 2nd and 3rd days after the first injection. On the 7th day angiography was reperformed to determine the chronic vasospasm. The first group (5 dogs) was the control group and received intrathecal saline which was equal to the amount of saline in which Iloprost was diluted. The second group (5 dogs) did not receive any treatment until the 7th day. The third group (6 dogs) received Iloprost intrathecally (total 10 micrograms kg-1). In the first two groups angiographic vasospasm was prominent. For the second group intraarterial Iloprost was given on the 7th day in order to evaluate its acute effect. However there was no evidence of resolution of vasospasm. In the third group, resolution of vasospasm was verified on angiograms. Electron microscope studies of basilar arteries of the first two groups revealed degenerative changes of the endothelial cells which were separated from each other and the elastic lamina was irregularly arranged. In the intrathecal Iloprost-treated group there was little thickening in the elastic lamina and the endothelial cells were almost normal in structure. These results can be considered as the evidence of the prophylactic effect of Iloprost given by the intrathecal route in the prevention of chronic cerebral vasospasm.