The normal behavior of Evans blue in the vacuolar apparatus of rat kidney and the changes in this normal behavior imposed by a magnesium deficiency were investigated. Since Evans blue binds tightly to serum albumin, and since Evans blue-albumin complexes are reabsorbed from the glomerular filtrate by pinocytosis by the cells of the renal proximal tubules, Evans blue served as a suitable marker of the vacuolar apparatus for these studies.

Rats were injected intravenously with Evans blue and sacrificed at either 1/2, 1, 3, or 12 hours post-injection. Kidneys were removed and homogenized. By fractional centrifugations at the different time periods post-injection, the net uptake of Evans blue by the total kidney and each subcellular fraction was observed. The amount of Evans blue taken up by the total kidney was shown to increase with time. Also a gradual increase in the amount of Evans blue in the nuclear fraction with time was seen. This was interpreted as an accumulation of Evans blue in large heterolysosomes.

The same experiments were applied to three day magnesium deficient rats. Differences observed from control kidney studies were: increased total kidney Evans blue at 3 hours after injection, increased heavy mitochondrial Evans blue at 3 hours, increased supernatant Evans blue at 3 hours, elevated sertim Evans blue, and increased urine Evans blue at 6 hours after injection. Possible explanations of these differences are discussed in the thesis.