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574 MUSCLES.
claims, by an autolysis of three months’ duration, .to have obtained two
to three times as much creatinine, directly from the muscle, and after
the addition of creatinine-free-gelatin four times as much, which is an
argument against the enzymotic destruction of creatinine in autolysis,
and he admits of the formation of creatine (or creatinine) from protein.
The autolytic experiments of Rothmann also indicate the formation of
creatine from a preliminary body, and the recent experiments of van
Hoogenhuyze and Verploegh make the enzymotic transformation
of creatine and creatinine probable. Mellanby positively denies the
re-formation of creatine as well as its destruction in autolysis entirely
free from bacteria. It is hard to draw positive conclusions from exper-
iments with autolysis. The transfusion experiments of Gottlieb and
Stangassinger with the kidneys and livers of dogs, not only point to
the ability of these organs to decompose creatine, but also for a re-forma-
tion of creatine in the liver. Further investigations are still very nec-
essary, especially as the conditions are probably not the same in all animals.
Thus Noel-Paton and Mackie l
found that the exclusion of the liver
in birds is without influence upon the creatine metabolism.
As will be discussed in Chapter XIV, no certain relationship
exists between the quantity of food protein and the extent of creatine
and creatinine elimination. On the contrary, several observations speak
for a relation between creatine formation and catabolism of organ pro-
tein, especially muscle protein and according to Noel-Paton 2
the
elimination of creatine in bird urine, which here corresponds to the
creatinine in the mammalian urine, is a measure of the protein catabo-
lism of the muscles.
Under all circumstances the proteins, and especially the guanidine
groups contained therein, are the mother-substance for the creatine or
creatinine. The guanidine occurs in the protein molecule as arginine;
but according to Otori it is not improbable that in the protein also
other guanidine groups exist. Nevertheless the observations of Jaffe 3
speak against the assumption as to a creatine formation from argin-
ine as he found that arginine subcutaneously injected did not cause
any increase in the elimination of creatine substances. But as the
introduced arginine was probably decomposed by the enzyme arginase,
because the urea elimination was greatly increased,4
does not exclude
1
Urano, Hofmeister’s Beitrage, 9; Gottlieb and Stangassinger, Zeitschr. f. physiol.
Chem., 52 and 55; Stangassinger, ibid., 55; Seemann, Zeitschr. f. Biol., 49; Roth-
mann, Zeitschr. f. physiol. Chem., 57; v. Hoogenhuyze and Verploegh, ibid., 57;
Mellanby, Journ. of Physiol., 36; Noel-Paton and Mackie, Journ. of Physiol. 45.
2
Journ. of Physiol.. 39.
•Otori, Zeitschr. f. physiol. Chem., 42, 43; Jaffe, ibid., 48.
4
See Thompson, Journ. of Physiol., 32 and 33.
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