Kinetic analysis of zinc metabolism and its regulation in normal humans

Abstract

Zinc metabolism was studied in 32 normal volunteers after oral (n = 25) or intravenous (n = 7) administration of 65Zn. Data were collected from the blood, urine, feces, whole body, and over the liver and thigh regions for 9 mo while the subjects consumed their regular diets (containing 10 mg Zn ion/day) and for an additional 9 mo while the subjects received an exogenous oral supplement of 100 mg Zn ion/day. Data from each subject were fitted by a compartmental model for zinc metabolism that was developed previously for patients with taste and smell dysfunction. These data from normal subjects were used to determine the absorption, distribution, and excretion of zinc and the mass of zinc in erythrocytes, liver, thigh, and whole body. By use of additional data obtained from the present study, the model was refined further such that a large compartment, which was previously determined to contain 90% of the body zinc, was subdivided into two compartments to represent zinc in muscle and bone. When oral zinc intake was increased 11-fold three new sites of regulation of zinc metabolism were identified in addition to the two sites previously defined in patients with taste and smell dysfunction (absorption of zinc from gut and excretion of zinc in urine). The three new sites are exchange of zinc with erythrocytes, release of zinc by muscle, and secretion of zinc into gut. Regulation at these five sites appears to maintain some tissue concentrations of zinc when dietary zinc increases.

Use of stable isotopes and mathematical modelling to investigate human mineral metabolism

“…These were: L (1,24); L(12,1); L(24,23). All other rate constants were not affected by dietary Cu level and their values did not differ by more than 4 % from those found by Wastney et al (1986). Compartment masses were also in agreement with those predicted by Foster et al (1979) and Wastney et al (1986).…”

“…These two assumptions lead to an inherent overestimation of EZP. Miller et al (1994) found this overestimation to be about 24 % when they fitted their data to a compartmental model (Wastney et al 1986). The subsequent paper (Miller et al 1998) found an overestimation of about 28 %.…”

“…There have been numerous compartmental models developed using radioisotopes, two of which (Foster et al 1979;Wastney et al 1986) were used as the basis for the stable-isotope model of Scott & Turnlund (1994b). They studied the effect of three different dietary levels of Cu on Zn metabolism in five adult men.…”

“…This value could not be calculated from the stable isotope data because the label was not returned from it within the 7 d study period. Previous radioisotope studies (Foster et al 1979;Wastney et al 1986) have estimated skeletal muscle and bone to contain approximately 95 % of the body Zn. Griffin et al (2000) compared results from this model with those from the same model but with an added erythrocyte compartment that exchanges with the plasma compartment.…”

Transient receptor potential melastatin type 7 channels are involved in zinc-induced apoptosis in gastric cancer

“…Optimal nucleic acid and protein metabolism, as well as cell growth, division, and function, require sufficient availability of zinc (Vallee and Falchuk 1993). The human body contains 2Á3 g zinc, and nearly 90% is found in muscle and bone (Wastney et al 1986). On the cellular level, 30Á40% of zinc is localized in the nucleus, 50% in the cytosol and the remaining part is associated with membranes (Vallee and Falchuk 1993).…”