PGE1 induced transcapillary transport of 51Cr‐EDTA in rat skin measured by microdialysis

Abstract

Interstitial fluid pressure (P_if) is a key determinant in increasing the transcapillary driving pressure, pulling fluid from the microcirculation into the interstitial space at the onset of acute inflammatory reactions and the oedema formation associated with these. Prostaglandin E₁ (PGE₁) induces lowering of P_if in rat skin which increases transcapillary transport of ⁵¹Cr-EDTA into the center of a tumor as measured by microdialysis. The aim of this study was twofold: First, to evaluate and develop the microdialysis technique thoroughly with regard to its suitability for investigating transcapillary water transport in rat skin using ⁵¹Cr-EDTA as a tracer. Secondly, to evaluate the effect of PGE₁ on transcapillary transport of ⁵¹Cr-EDTA. This study demonstrates that PGE₁ increases transcapillary transport of ⁵¹Cr-EDTA into skin interstitium. There were no significant differences between the experimental probe and the control probe when calculations from the entire experiment (90 min) were compared. On the other hand, significant differences were observed by examining the experiment in smaller time intervals. PGE₁ increased transcapillary transport of ⁵¹Cr-EDTA during the first 15 min when administered through the microdialysis probe. This observation suggests that increased blood flow and/or permeability-surface area product are responsible for raising the transcapillary transport of ⁵¹Cr-EDTA, i.e. the transport is diffusion limited. Administration of PGE₁ through the probe rather than around the probe resulted in less scatter between experiments than when PGE₁ was injected subcutaneously around the probe.