Abstract
The depancreatized dogs used in these experiments differed from most animals used for previous work of a similar nature, in that they were allowed, by the use of insulin, to make a perfect recovery from the operation and anesthetic. These dogs, after the withdrawal of insulin, were kept on a protein diet and generally showed a progressive rise in the respiratory quotient, after the first week or two of the experiment. The R.Q. might be maintained far above the “diabetic” level for as long as two weeks, and in some cases rose above 0.900. At a very early stage of the experiment, the second or third day in some cases, the D:N ratio had usually fallen below 2.8:1 and might be maintained far below this level for almost a month (e.g., dog 9, Table VI). The administration of 50 gms. of dextrose in addition to the regular diet resulted in the retention of considerable amounts of this sugar, which was not excreted on subsequent days. This retention of glucose was often as much as 50 per cent of the amount administered, and in one case (dog 14, Table IX) where 100 gms. dextrose was given, the retention actually amounted to 68 gms. In a few instances the total amount of glucose excreted on the day of dextrose administration was less than that given, so that even if it could be imagined that on those days the animal produced no glucose from other sources, there would still be a retention. The dextrose administration often caused a decided rise in the R.Q. The progressive increase in this effect, as the experiment advanced, is beautifully illustrated in the results of Table IX. The administration of dextrose also caused a sharp drop in the total ketone excretion, and usually exerted a definite protein-sparing action. When the CO2 combining power or total CO2 content of the blood was determined at intervals, very little fall in these values was observed to occur throughout the experiment. Dogs 9 and 14 (Tables VI and IX) actually show a rise in these values during the later stages of the observation. The administration of dextrose invariably caused a temporary retention of CO2. It is evident, therefore, that the “blowing-off” of CO2 was not a factor influencing the R.Q. The retention of CO2 associated with the diminished ketone excretion probably accounts, as Wierzuchowski (1926) has suggested, for those cases in which the administration of dextrose had little effect on the R.Q. The fat content of the liver, where determined, was found to be very much lower than the values reported by Macleod (1926) for diabetic dogs deprived of sugar and insulin for shorter periods. Thus, dog 6 (Table IV), which demonstrated the oxidation of carbohydrate very clearly, had a liver fat content of only 1.5 per cent at the termination of the experiment. The three dogs, which were returned to meat-sugar-pancreas diets with insulin, made prompt recoveries. Two of these, which were put back on experiment after a short interval, again gave “diabetic” respiratory quotients.