[Development of a radioligand assay for quantifying specific prostaglandin E1 binding in ischemic ulcers]

Ulcers of the lower extremities are of immense socioeconomical importance. Prevention and therapy of these trophic lesion are hence of great interest. In granulation tissue of ischemic ulcers Laser Doppler flow was previously shown to be higher compared to that in ischemic/adjacent skin or in ulcer without granulation tissue. Intravenous infusion of prostaglandin E1 significantly increased Laser Doppler flow. The present study was designed to test the hypothesis whether the increased baseline and prostaglandin E1-stimulated perfusion of granulation tissue is due to an increased number of prostaglandin E1-receptors in granulation tissue. Therefore, a radioligand binding assay was developed. In an initial pilot study the density of the prostaglandin E1-receptors in granulation tissue of ulcers was compared to that in ischemic/adjacent skin in 8 patients suffering from peripheral arterial occlusive disease requiring debridement or amputation of limbs because of ischemic lesions. The amount of specific binding sites detected was not significantly different between granulation tissue and ischemic/adjacent ulcer tissue. However it cannot be excluded that a possible difference might be detectable with more sensitive assays. In the future we hope to establish a more sensitive assay in order to be able to answer the initial question, whether there is a difference concerning the density of prostaglandin E1 receptor sites in granulation tissue and ischemic/adjacent skin.