Development of a radioligand assay for the quantification of the specific prostaglandin E-1-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 w ithout granulation tissue. Intravenous infusion of prostaglandin El signifi cantly increased Laser Doppler flow. The present study was designed to test the hypothesis whether the increased baseline and prostaglandin El-stimula ted perfusion of granulation tissue is due to an increased number of prosta glandin El-receptors in granulation tissue. Therefore, a radioligand bindin g assay was developed. In an initial pilot study the density of the prostaglandin E-1-receptors in granulation tissue of ulcers was compared to that in ischemic/adjacent ski n in 8 patients suffering from peripheral arterial occlusive disease requir ing debridement or amputation of limbs because of ischemic lesions. The amount of specific binding sites detected was not significantly differe nt between granulation tissue and ischemic/ adjacent ulcer tissue. However it cannot be excluded that a possible difference might be detectable with m ore sensitive assays. In the future we hope to establish a more sensitive a sssay in order to be able to answer the initial question, whether there is a difference concerning the density of prostaglandin Fl receptor sites in g ranulation tissue and ischemic/ adjacent skin.