Dinitrophernol exerted no significant influence on the
excretion of urinary nitrogen. This contrasts with the
very considerable increase in nitrogen excretion observed in patients undergoing treatment with thyroid, in which
respect the cases under consideration were no exception.
It is apparent, therefore, that the excess metabolism due
to dinitrophenol is not conducted at the expense of exogenous or endogenous protein to any appreciable extent, whereas a small but significant part of the excess
metabolism produced by thyroid is due to protein.
Reference to Chart II shows that a considerable fall in
the respiratory quotielt occurred during the period of
dinitrophenol administration to Case 3, the average basal
respiratory quotient for the control period being 0.84,
while on dinitrophenol the average was 0.74. Again, in
Case 1, where frequent determinations were made during
the two hours following the administration of single doses
of dinitrophenol, a tendency for the respiratory quotient
to fall was usually noted, and there Was never a significant
rise. In Case 2 the respirator! quotient remained remarkably -low throughout the control period; and remained
low during the whole period of dinitrophenol- administration' (see Chart I).
In the present series of experiments
the exhibition of thyroid caused no very significant variation in the respiratory quotient, though our previous
experience suggests that on the average the effect of
thyroid is to raise the respiratory quotient slightly.10
These results would seem to indicate that the excess
metabolism produced by dinitrophenol is conducted at
the expense of fat rather than at the expense of carbohydrate or protein, though this interpretation is subject
to the criticism that the method of approach is an indirect
one. From the fact that no ketone bodies were ever
discovered in the urine, it would seem that any fat used
was completely and satisfactorily broken down.
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