Lipoids in the Kidney of Adrenal Insufficiency.

The presence of large amounts of lipoid in the cortex of the kidneys of adrenalectomized cats has been described. 1 The staining reactions indicated the presence of cholesterin-esters, cholesterinfatty acid mixtures, and neutral fats.

A study has been made of the chemical nature of these substances. Thirteen completely adrenalectomized cats and 8 normal cats were used in this work. The adrenalectomized cats survived an average of 12.7 days, the survival periods varying from 5 to 26 days. Some of the animals were injected daily with adrenal extracts.

For the chemical analysis, one gram of fresh, ground kidney is extracted with a solution of chloroform and alcohol, 1-3, and made up to 20 cc. Aliquot parts are taken for the following determinations. One portion is evaporated to dryness and weighed for total lipoids. The free acid is titrated directly with .01 N NaOH. In calculating the weight, 280 is taken as the molecular weight. The volatile acids are separated from the non-volatile by saponifying, acidifying, and aerating over a boiling water bath. The residue is titrated with .01 N NaOH for non-volatile acids and the contents of the receiving tube for the volatile acids. The molecular weight of the non-volatile constituents is taken to be 280, that of the volatile to be 100. Cholesterol and phosphorus are determined by the standard colorimetric methods. The iodine value is reported in milligrams of iodine absorbed per gram of original kidney material.

The per cent increase in iodine absorbed in the kidneys of adrenalectomized cats is less than the per cent increase in the total lipoids. Therefore, the extra fat contains a smaller proportion of double bonds than the normal. The kidney phosphorus decreases after removal of the adrenals, even though the total lipoids markedly increase.