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Department of Nutrition, Rutgers, The State University of New Jersey, New Brunswick, NJ 08903
Quantitative measurements of zinc absorption were made using the isolated, vascularly perfused rat intestine as a model. The perfused intestine retains the ability to discriminate between absorption processes for calcium, copper, iron and zinc. Measurements of zinc absorption by the perfused intestine, using atomic absorption spectrophotometry, indicated the presence of a zinc pool within intestinal mucosal cells. The zinc concentration in the lumen of the perfused intestine was directly related to the amount of zinc that appeared in the vascular perfusate. Intestines obtained from zinc-deficient animals exhibited an ability to process greater quantities of zinc which resulted in enhanced absorption. The maximal rate of zinc absorption was 229 nmoles per hour with intestines from rats fed adequate amounts of zinc and 627 nmoles per hour when a zinc-deficient diet was fed. Administration of zinc to rats before isolation and perfusion of the intestine resulted in greater intracellular retention of zinc taken up from the lumen and correspondingly lesser amounts (75 nmoles per hour) transferred to the vascular supply. These data provide quantitative evidence that the perfused intestine retains its ability to exercise homeostatic control over the zinc absorption process and that the intestinal cell is a major site of regulation.
KEY WORDS: zinc absorption intestinal perfusion regulation
1 This work was supported by N.I.H. Grant No. AM 18555 from the National Institute of Arthritis, Metabolism and Digestive Diseases, DHEW; the Charles and Johanna Busch Memorial Fund of Rutgers University and as Project No. 311 of the New Jersey Agricultural Experiment Station.
2 Presented in part at the American Institute of Nutrition meeting, Dallas, TX, April 1979. Abstract published in Fed. Proc. 37, abs. #303.
3 Present address: Miami Valley Laboratories, The Procter and Gamble Co., Cincinnati, OH, 45247.
4 To whom reprint requests should be sent.
Manuscript received 4 June 1979.
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