Comparative study of phase II biotransformation in rabbit ocular tissues

J. B. Watkins, D. P. Wirthwein, R. A. Sanders

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Abstract

To assess the biotransformational capability of ocular tissues in the rabbit, representative phase II enzymes were assayed in five tissues from the eye, and in the liver, kidney, and intestine. Within the eye, the iris/ciliary body exhibited the highest glutathione S-transferase activity, whereas the cornea possessed the highest specific activities for N-acetyl-, sulfo-, and UDP-glucuronosyl-transferases. Cornea, iris/ciliary body, choroid, and retina exhibited significant activities of p-aminobenzoic acid N-acetyltransferase, 2-naphthol sulfo-transferase, and 1-chloro-2,4-dinitrobenzene glutathione S-transferase. Despite its size and protein content, lens displayed little or no biotransformational activity. Only the iris/ciliary body conjugated sulfobromophthalein with glutathione. UDP-glucuronosyltransferase activity varied depending on tested substrates and tissues. When compared to liver, kidney, or intestine, N-acetyltransferase activity in the iris/ciliary body nearly matched the rate measured in kidney, glutathione S-transferase activity in cornea and iris/ciliary body was nearly 70 and 89%, respectively, of the rate in intestine, and corneal sulfotransferase activity was greater than that in kidney. These data suggest that biotransformation pathways are present in the eye, and particularly in ocular tissues having adequate blood supply or interfacing with the external environment.

Original languageEnglish (US)
Pages (from-to)708-713
Number of pages6
JournalDrug Metabolism and Disposition
Volume19
Issue number3
StatePublished - Jun 24 1991

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ASJC Scopus subject areas

  • Pharmacology
  • Pharmaceutical Science

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Watkins, J. B., Wirthwein, D. P., & Sanders, R. A. (1991). Comparative study of phase II biotransformation in rabbit ocular tissues. Drug Metabolism and Disposition, 19(3), 708-713.