Reducing Substances of the Normal Urine. I. Effects of Insulin Injection

Abstract

This paper embodies a study of the effect of insulin injection upon the excretion of the reducing substances of the normal urine, with special regard to the fermentable fraction. The observations were made on dogs.

There are two articles in the literature pertinent to our subject. Salmon 1 finds that, in man, there is a correlation between the blood sugar level and the normal excretion of reducing substances in the urine. Van Creveld and Van Dam 2 eviscerated frogs, except for kidneys and ureters, cannulated the latter, and perfused through the renal artery a fluid similar to Ringer's solution. To the perfusion were added various concentrations of glucose, and the glucose concentration of the recovered perfusion fluid and of the artificial urine was determined by the micrometric method of Bang. They noted that as the concentration of glucose in the perfusion fluid was increased, there was a corresponding increase in the concentration of glucose in the artificial urine. Where insulin had been injected before the animal was eviscerated, or where insulin was added to the perfusion fluid, there was a profound fall in the concentration of glucose in the urine, and an increase in the concentration of glucose in the fluid recovered from the renal vein. These workers concluded that the presence of insulin in the kidney decreases the passage of glucose into the urine, and ascribed this action to the existence of a “renal at tacking point” for insulin .

While the results of this experiment were dramatic and doubtless important, the mode of attack was such as to involve distinctly unphysiological conditions, notably in the use of an artificial renal environment. Further, the estimations involved the concentration of glucose in the urine and in the recovered fluid, rather than the quantity of glucose excreted per unit of time.