The aim of the present study was to investigate the edema induced by leukotriene D₄ (LTD₄). Edema is the gross effect of increased blood flow and capillary permeability. Our objective was to elucidate the effect of LTD₄ on edema generation without the influence of the concomitantly increased blood flow induced by this potent vasodilator. A new method was outlined measuring the exudation through skin windows of a macromolecular tracer ([¹³¹I]albumin) and a micromolecular tracer ([⁹⁹Tc]pertechnetat). Exudation of [¹³¹I]albumin is a function of enhanced vascular permeability and interstitial transport and blood flow, whereas that of [⁹⁹Tc] pertechnetat is mainly a function of blood flow. Thus a ratio of the 2 exudate measurements gives a specific estimate of the changes in vascular permeability and interstitial transport.

Histamine was employed to establish the method. A dose–response relation was found for histamine in the dose range of 10^-4 to 10^-7 M. The effect of 10^-5M LTD₄ on vascular permeability and interstitial transport of macromolecules was indistinguishable from that of histamine in the same concentration. This property together with their well-known vasodilatory capabilities indicate that the leukotrienes of the slow-reacting substance of anaphylaxis may play a role in the vascular changes in the allergic-inflammatory reaction.