QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Koo, S. I. Articles by Turk, D. E. Search for Related Content PubMed PubMed Citation Articles by Koo, S. I. Articles by Turk, D. E.

Effect of Zinc Deficiency on Intestinal Transport of Triglyceride in the Rat^1,2,3,

Department of Food Science, Clemson University, Clemson, South Carolina 29631

Ultrastructural and biochemical changes in the intestinal epithelium during the process of active triglyceride absorption were studied in rats fed a zinc-deficient diet as compared with those of pair-fed and ad libitum-fed zinc-supplemented controls. The rate of triglyceride absorption markedly decreased in zinc-deficient rats. Despite a significant reduction in pancreatic lipase activity, the digestion of triglycerides proceeded normally in the zinc deficient rats, as evidenced by no apparent signs of diarrhea (or steatorrhea) and by the appearance of the hydrolytic products such as free-fatty acids and monoglycerides in the intestinal mucosa. The mucosa uptake of digested lipids and resynthesis of triglycerides in the mucosa from deficient rats were normal. Ultrastructural and chromatographic analysis of the mucosal lipids indicated a massive accumulation of lipid droplets, predominantly in the form of triglycerides. The primary defect in lipid absorptive processes in zinc-deficient rats occurred in the formation of chylomicrons. The lipid droplets in the mucosa of deficient rats were physically unstable. This instability was shown by coalescence of droplets which did not appear to be membrane-bound. Coalescing lipid droplets ranged from 2.0 to 4.0 µ in diameter. The absorptive cells were not able to discharge lipid droplets of this size into the intercellular spaces and hence into the lamina propria, resulting in the accumulation of the large droplets within the mucosa. This exit block to the movement of lipid droplets out of the mucosal cell appeared to be due to the failure, in zinc-deficiency, of the mucosal synthesis of proteins required for the formation of chylomicrons. Ultrastructural observations demonstrated changes in the subcellular organelles related to protein synthesis, including a marked reduction in granular endoplasmic reticulum and a quiescent appearance of the Golgi-complex.

KEY WORDS: • zinc • triglyceride • intestine • transport

¹ This manuscript was taken in part from a dissertation submitted to the Graduate School of Clemson University by Sung I. Koo in partial fulfillment of the requirements for the degree of Doctor of Philosophy.

² Published with the approval of the Director of the South Carolina Agricultural Experimental Station as Technical Contribution No. 1395.

³ Presented in part at the 73rd meeting of the Southern Association of Agricultural Scientists and published as an abstract in the Food Science and Technology section, SAAS, 1976, 13, 7 (Abstr.).

⁴ Present address: Department of Physical Biology, New York State Veterinary College, Cornell University, Ithaca, New York 14850.

⁵ Send reprint requests to: D. E. Turk, Food Science Department, Clemson University, Clemson, South Carolina 29631.

Manuscript received 26 August 1976.