[Calcium and magnesium concentrations of the renal cortex in the rat. Comparison of 3 methods of tissular extraction of the principal cations].

We describe three methods for extraction of main tissular cations : a) dry ashing method; b) wet ashing method with HNO3; c) wet method on fresh tissue with HCIO4. This study allows the determination of tissular concentrations of calcium, magnesium in renal cortex of the Rat. Our findings show : a loss of Na, K cations probably by volatilization with dry ashing method ; inability for K determination when HCIO4 method is used ; tissular concentrations are : 4,7 mEq Ca ; 21,6 mEq Mg per kg of wet tissue (wet ashing method with HNO3) ; recovery percentage for magnesium is above 100 % (as previously shown by other authors) ; the dry ashing method is less suitable for extraction than the two other methods ; both wet methods lead to similar results and to a recovery percentage near 100 %.