Abstract
Poly R-478 (Dynapol Corp, Palo Alto, CA) is one of a new family of polymeric food dyes which have been shown to be highly water soluble, non-toxic and non-absorbable (J Cosmet Toxicol 19:687,1981). To evaluate Poly R-478 as a NAM for absorption studies, it was compared to PEG-4000 in a protocol for the measurement of bile salt absorption (Ped Res 18: 213A, 1984). Male rats (n=15; age 40 ± 5 days; wt 154 ± 33 g -mean ± SD) were anesthetized, bile ducts were cannulated and the jejunum (J) catheterized. To compare the distribution of the NAMs, a group of rats (n=7) had 1 ml of a solution containing 1 to 10 mM taurocholate (TC), 3H-TC, and both 14C-PEG and Poly R-478 instilled into the J. To measure TC absorption, a second group (n=8) received solutions containing TC, 3H-TC and Poly R-478. At the end of the study, J and ileum were divided into 8 segments, homogenized, and digested in 1M KOH. The absorbance of Poly R-478 at 515 nm was found to be linear from .0002% to .02g%. The Poly R-<478 concentration in each segment was measured by spectrophotometry at 515 nm and was used to calculate TC absorption.
Poly R-478 recovery was 96.3 ± 9.7%. The distributions of Poly R-478 and 14C-PEG were significantly correlated (r=.91, p<.001). The TC absorption rate was linearly related to the TC concentration (y=.54x+.20, r=.98, p<.001) and was identical to data calculated using PEG-4000.
Poly R-478 is an effective NAM whose advantages include solubility in water, stability, easy and precise concentration determinations and non-radioactivity, allowing the simultaneous use of multiple radio-labeled substrates. The extensive use of this dye family in the food industry attests to its applicability to human and animal absorption studies.
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Stahl, G., Fayer, J. & Watkins, J. 734 EVALUATION OF POLY R-478, A NEW POLYMERIC FOOD DYE, AS A NON-ABSORBABLE MARKER (NAM). Pediatr Res 19, 233 (1985). https://doi.org/10.1203/00006450-198504000-00764
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DOI: https://doi.org/10.1203/00006450-198504000-00764