Author
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MOMCILOVIC, BERISLAV - U OF ZAGREB |
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Submitted to: Trace Elements in Man and Animals International Symposium
Publication Type: Abstract Only Publication Acceptance Date: 5/19/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: The effect of idiorrhythmic zinc dose-rate feeding (Momcilovic B., J. Nutr. 125:2687-2699, 1995) upon Ca, P, Mg, Na, K, Fe, Zn, Cu, and Mn was studied in the femur of weanling Sprague-Dawley male rats. In idorrhythmic feeding the dose (x) is viewed over the time of the entire experimental epoch as a dose-time equivalent modulo (Mx) which can be divided into a series of equal products of different dose and frequency (idiorrhythm, Ix). Three different zinc dose-time equivalent modulos (Mx): M3, M12, and M48 were used, which provided an average of 3, 12, and 48 mg Zn x kg**-1 diet x d**-1 over a 48-day idiorrhythmic epoch, respectively. Each Mx had eight analogous Ix of 8 animals each where dose was coupled to frequency in a regularly recurring pattern to provide the same amount of nutrient, albeit at a different rate: I = Mx/1, 2Mx/2, etc. to 8Mx/8. The amount of zinc in the nominator was corrected by the sequential number of zinc dosing days in the denominator as no zinc was provided between zinc dosing days. The effects of Mx, Ix, and Mx x Ix interaction, were analyzed by two-way ANOVA. Femur weight and femur zinc (amount and concentration) were affected by Mx, Ix, and Mx x Ix interaction. Idiorrhythmic zinc dose-rate feeding showed an Mx dependent effect upon the amount and concentration of all the minerals studied in the femur. Evidently, an interactive, dynamic, and multi-element homeostatic equilibration occurs at a different set point for any given physiological amount of dietary zinc intake. The absence of a fixed threshold supports the view that the RDAs and RfDs for minerals should be expressed in a range format. |