Polymeric dyes: useful nonabsorbable reference markers for intestinal perfusion studies in animals

Area of Science:

• Biochemistry
• Physiology
• Analytical Chemistry

Background:

• Intestinal perfusion studies require reliable nonabsorbable reference markers.
• Existing markers may have limitations in stability, quantification, or physiological interaction.

Purpose of the Study:

• To evaluate the suitability of two novel polymeric dyes, polyporphyre (R-478) and polycyanine (R-411), as nonabsorbable reference markers for intestinal perfusion.
• To assess their spectrophotometric properties, stability, and interactions with biological components.

Main Methods:

• Spectrophotometric analysis of dye concentration and stability across pH and light exposure.
• Gel permeation chromatography for molecular weight determination.
• Assessment of binding interactions with bile acids, fatty acids, bilirubin, and mucus.
• Evaluation in a rat jejunal perfusion model comparing to polyethylene glycol 4000.

Main Results:

• Dyes quantified spectrophotometrically (0.03-5 microM) with no osmotic effect, light stable, and stable across pH 1-11.
• Molecular weight ~40,000 Da; no hydrophobic binding sites observed.
• No interference with bilirubin determination or bile acid assays; minimal radioactivity quenching.
• Effective removal via anion exchange or protein precipitation.
• Identical performance to polyethylene glycol 4000 in rat jejunal perfusion; no influence on glucose absorption or mucus binding.

Conclusions:

• Polyporphyre and polycyanine are stable, quantifiable, and non-interactive polymeric dyes suitable for intestinal perfusion studies.
• These dyes offer a reliable alternative to existing reference markers.
• Further validation in diverse physiological conditions is warranted.