OBSERVATIONS ON THE ADMINISTRATION OF DEHYDROASCORBIC ACID IN DIABETOGENIC DOSES TO ALBINO RATS

¹ The Department of Clinical Chemistry, University of Edinburgh, and the Clinical Laboratory, Royal Infirmary, Edinburgh

1. Observations were made on the ascorbic acid (ASA) and "total ascorbic acid" (TASA = ASA + (dehydroascorbic acid) DHA + (diketogulonic acid) DKA) concentrations in the liver, kidney, pancreas and adrenals before and after the intravenous injection of DHA in diabetogenic doses or of ASA to male and female albino rats.

2. Immediately following the dose of DHA, the concentration of TASA rose about 50-fold in the kidneys. The concentration rose in the liver (10- to 16-fold) and pancreas (7- to 10-fold). The DHA which entered the tissues was rapidly reduced. The extent of reduction in the liver was more than 80 per cent, whereas in the kidneys and pancreas only about 50 per cent reduction took place. Twenty-four hours later most of the excess TASA had disappeared. Following a second dose, the concentrations in the tissues presumably rose temporarily, but at the end of 24 hours further accumulation had not taken place. Following a third dose, rapid reduction to ASA was again observed. The concentrations in the tissues were almost normal 8 days later.

3. Compared with DHA, the administration of ASA under similar conditions led to a greater rise in the concentration in the pancreas; the kidneys concentrated to the same extent as before whereas the liver concentrated much less.

4. The intravenous injection of diabetogenic doses of DHA or of similar amounts of ASA after preliminary desensitization caused an immediate depletion of adrenal ascorbic acid. Some depletion was observed following the intravenous injection of only 0·2 g./kg. body weight of dehydroascorbic acid (the desensitizing dose). The fall was more marked after dehydroascorbic acid and in the male rat. Twenty-four hours later a restoration in concentration of adrenal ascorbic acid occurred together with a significant rise in adrenal weight.

Note:

The author wishes to thank Dr. C. P. Stewart for his continued interest and help during this work.