Increased plasma pyridoxal-5′-phosphate when alkaline phosphatase activity is reduced in moderately zinc-deficient rats
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It is generally believed that the zinc metalloenzyme alkaline phosphatase is required to hydrolyze phosphorylated forms of vitamin B-6 prior to their use. To test this hypothesis, rats were fed a liquid diet containing either adequate or moderately low zinc during gestation and lactation. Zinc deficiency was produced in dams evidenced by significant reductions in zinc concentration of plasma (49%), liver (25%), and femur (24%), and plasma alkaline phosphatase activity (48%). Plasma pyridoxal-5′-phosphate (PLP), which significantly increased (61%) in these same rats, was negatively correlated (r=−0.74,P<0.02) with plasma alkaline phosphatase activity. Maternal liver PLP concentration was unaffected by zinc status. The zinc and vitamin B-6 relationship seen in dams was less observable in offspring. Stimulation of erythrocyte alanine aminotransferase activity by exogenously added PLP in vitro tended to be higher in both moderately zinc-deficient mothers and their offspring, but the difference was not significant. Our results support the hypothesis that alkaline phosphatase activity is required for the hydrolysis of plasma PLP. Our results also suggest that zinc status as alkaline phosphatase activity should be defined in an individual if plasma PLP is to be used as an indicator of vitamin B-6 status.
Index EntriesZinc vitamin B-6 alkaline phosphatase pyridoxal-5′-phosphate
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- 1.A. H. Merrill, Jr. and F. S. Burnham, inPresent Knowledge in Nutrition, 6th ed., M. L. Brown, ed., Nutrition Foundation, Washington, DC, 1990, pp. 155–162.Google Scholar
- 2.J. E. Leklem, inModern Nutrition in Health and Disease, 8th ed., M. E. Shils, J. Olson, and M. Shike, eds., Lea and Febiger, Philadelphia, 1993, pp. 383–394.Google Scholar
- 3.A. S. Prasad,J. Am. College Nutr. 4, 591–598 (1985).Google Scholar
- 4.K. M. Hambidge, C. C. Casey, and N. F. Krebs, inTrace Elements in Human and Animal Nutrition, 5th ed., W. Mertz, ed., Academic Press, New York, 1986, pp. 1–137.Google Scholar
- 9.Subcommittee on Laboratory Animal Nutrition, inNutrient Requirements of Laboratory Animals, 3rd ed., National Academy of Sciences, Washington, DC, 1978, pp. 7–37.Google Scholar
- 10.G. A. Herzfeld, L. A. Reynolds, and S. J. Richey,Nutr. Reports Internatl. 31, 849–856 (1985).Google Scholar
- 14.American Veterinary Medical Association Panel on Euthanasia,J. Am. Vet. Med. Assoc. 188, 252–268 (1986).Google Scholar
- 19.R. G. D. Steel and J. H. Torrie,Principles and Procedures of Statistics, 2nd ed., McGraw-Hill, New York (1980).Google Scholar
- 20.H. H. Sandstead,Am. J. Diseases Child. 145, 853–859 (1991).Google Scholar