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Differentiation of light-dye effects in the microcirculation
F N Miller1, D E Sims, D A Schuschke
1Department of Physiology and Biophysics, University of Louisville, Kentucky 40292.
Microvascular Research
|September 1, 1992
Summary
Light activation of fluorescein isothiocyanate causes microvascular toxicity. Low doses cause histamine release-mediated leakage, while higher doses induce platelet thrombi and vessel damage.
Area of Science:
- Microcirculation research
- Photodynamic therapy
- Vascular toxicology
Background:
- Photosensitive compound activation is used in tumor treatment and microcirculation studies.
- Deleterious effects can complicate experimental interpretations.
- Mechanisms of toxicity and light doses for reactions are not well-defined.
Purpose of the Study:
- To evaluate toxic reactions of light-activated fluorescein isothiocyanate in rat cremaster muscle.
- To define dose-dependent toxic responses and underlying mechanisms.
Main Methods:
- In vivo fluorescent television microscopy of rat cremaster muscle.
- Electron and light microscopy for morphological analysis.
- Assessment of macromolecular leakage, platelet activation, and cellular damage.
Main Results:
- 120 J/cm2 caused macromolecular leakage and platelet activation, partially inhibited by pericytes and histamine release.
- Higher light doses (720 J/cm2) led to significant venule obstruction via platelet thrombi, exacerbated by indomethacin.
- 720 J/cm2 also caused endothelial/smooth muscle cell damage, gap formation, and inflammatory cell/protein accumulation.
Conclusions:
- Fluorescein isothiocyanate activation induces dose-dependent microvascular toxicity.
- Histamine release from mast cells contributes to low-dose macromolecular leakage.
- Prostaglandins may inhibit platelet thrombus formation at higher light doses.