[Delay and magnitude of plasma and bone responses and of stable, residual, leachable hair fractions to two different levels of K, Na, Ca, Mg, P intake in rat (author's transl)].

Two groups of 20 adult female rats are fed ad libitum with two diets differing in K, Na, Ca, Mg, P content, being for the first diet (in g/kg) : 14.9, 0.5, 6.3, 0.82, 1.25, respectively, and for the second : 1.6, 8.3, 2.4, 0.17, 5.76, respectively. Five rats of each group are killed after 1, 2, 3, 4 months. This study compares the delay and magnitude of plasma and bone responses and of three different hair fractions to the two levels of intake. Hair is not clipped in order to estimate the delay in response of already grown hair to mineral intake modification. The three following hair fractions are analyzed : a) leachable fraction, determined in the solution used for washing hair (equal parts water-ethanol-ether) ; b) stable hair fraction, determined in hair obtained after the previous washing ; c) residual hair fraction, determined in hair washed with a non-polar detergent. The following results are observed : 1) K : A plasma variation is obtained as early as month 1 (P less than 0.005). The leachable fraction is modified from month 3 (P less than 0.001) and the stable hair fraction on month 4 (P less than 0.025). 2) Na : There is no variation at the plasma level. The leachable fraction response appears as early as month 1 (P less than 0.001) and the hair stable fraction at month 2 (P less than 0.025). 3) Ca : There is no variation at the plasma level. The leachable (P less than 0.025) and hair stable (P less than 0.01) fractions show a response from month 3. 4) Mg : A rapid and intense variation is observed at the plasma level as early as month 1 (P less than 0.001). The hair stable fraction shows a response at month 2 (P less than 0.05) and the leachable and residual fractions at month 3 (P less than 0.05). Bone Mg is modified as early as month 1 (P less than 0.005). 5) P : Plasma response at month 4 (P less than 0.05) is weak and late. An important variation is observed from month 2 in the leachable fraction (P less than 0.005) and at month 3 in the hair stable fraction (P less than 0.005). Residual hair fraction provides no valuable information. Consequently, the more common method of washing hair with a detergent should be excluded, at least for the nutritional exploration of the minerals involved in this study.