Relationship between Small-Intestinal Transit Rate and Intestinal Absorption of ¹⁴C-labelled Mannitol and ⁵¹Cr-labelled Ethylenediaminetetraacetic Acid in Healthy Subjects

Abstract

Background: Although the small-intestinal transit rate is generally considered to influence the urinary excretion of markers of intestinal permeability, no study has until now formally addressed the importance of this influence in humans. Methods: Ten healthy subjects ingested a test solution containing ^99mTc-labelled diethylenetriaminepentaacetic acid (^99mTc-DTPA), ¹⁴C-labelled mannitol (¹⁴C-mannitol), and ⁵¹Cr-labelled ethylenediaminetetraacetic acid (⁵¹Cr-EDTA). After ingestion, the small-intestinal transit rate of ^99mTc-DTPA was measured with the gamma camera technique. Urine was collected for time periods of 0–2 h, 2–4 h, and 4–6 h to measure the excretion of absorbed ¹⁴C-mannitol and ⁵¹Cr-EDTA. Moreover, the distribution volume and plasma clearance of ¹⁴C-mannitol and ⁵¹Cr-EDTA were determined in each subject. Results: A positive correlation was found between mean small-intestinal transit time and 0- to 6-h urinary excretion of ¹⁴C-mannitol. The study did not show any correlation between small-intestinal transit rate and 0- to 6-h urinary excretion of ⁵¹Cr-EDTA. Urinary excretion of neither ¹⁴C-mannitol nor ⁵¹Cr-EDTA was affected by distribution volume or urine volume. A positive correlation was observed between plasma clearance and 0- to 6-h urinary excretion of ¹⁴C-mannitol, whereas plasma clearance did not influence the urinary excretion of ⁵¹Cr-EDTA. Conclusions: Small-intestinal transit rate seems to have a significant effect on 0- to 6-h urinary excretion of ¹⁴C-mannitol, whereas small-intestinal transit rate does not influence the timed urinary excretion of ⁵¹Cr-EDTA.

Key Words:

• Intestinal permeability
• small-intestinal transit rate