Microvascular effects of iloprost in the hamster cheek pouch.

In the hamster cheek pouch, microvascular effects of iloprost at a nonhypotensive dose include vasodilatation at the level of arterioles and venules without changes in microvascular permeability, increased number of perfused capillaries/cm2, prevention of microvascular spasm and capillary ischemia as caused by LTD4, and inhibition of histamine- and 5-HT-induced venular leakage of FITC-dextrane. As regards the effects on basal vessel tone, capillary density, and prevention of LTD4 effects, PGE1 had similar effects as also shown by others in the human cutaneous microcirculation. However, PGE1 did not prevent the microvascular leakage caused by histamine. The Ca2+-antagonist nifedipine, apart from arteriolar vasodilatation, neither increased venular diameter and capillary perfusion nor prevented the effects of LTD4 and histamine. The microvascular actions of iloprost by improvement of tissue perfusion and prevention of mediator-induced tissue edema and vasospasm could contribute to the beneficial effects observed in ischemic diseases.