Effect of Hepatic Injury on Vitamin C Excretion in Fasting Dogs. ∗

Abstract

Fasting dogs normally excrete a urinary substance that appears to be iderctical with Vitamin C. This substance reduces 2:6 dichlorphenol indophenol and gives the color reaction used in the estimation of the vitamin. Moreover, it was established in these investigations that the reducing substance further resembles vitamin C in that it is not precipitated by mercuric acetate and is destroyed by incubation with the pressed juice of cauliflower. Dogs given a normal laboratory diet excreted increased amounts of substances that reduced the indophenol, but most of these could be removed from the urine by precipitation with mercuric acetate. After the dogs had been put on a fast, the excretion of reducing substance decreased over a period of about 4 days and thereafter the elimination remained constant throughout the period of fasting which usually was from 21 to 30 days.

The biological identity of the reducing substance excreted by the fasting dog has not been established, but Musulin, Tully, Longenecker and King 1 have shown that the reducing substance excreted in the urine by rats has antiscorbutic properties.

Experinzental. Female dogs were fasted for a preliminary control period of about 10 days and for the duration of the experiment but were allowed free access to drinking water. The animals were kept in metabolism cages permitting quantitative collection of all urine in dark colored bottles containing acetic acid. At the end of each 24-hour period the dogs were catheterized.

Hepatic injury was induced by 3 different methods. One method was the induction of deep chloroform anesthesia by inhalation for one hour, and another was the administration of carbon tetrachloride by stomach tube.