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594 MUSCLES.
According to Siegfried the amount of phosphocarnic acid is dimin-
ished during activity. Macleod * claims that this is true only for
intense muscular activity, and the mother-substance of lactic acid can
at least in part be phosphocarnic acid. The question as to the forma-
tion of lactic acid during activity, and the origin of the phosphocarnic
acid is certainly in many points somewhat undecided; the general
view seems to be, that during work lactic acid is formed, which transforms
a part of the diphosphates into monophosphates.
The amount of proteins in the removed muscles is, according to the
earlier investigators, decreased by work. The correctness of this state-
ment is, however, disputed by other investigators. Earlier reports in
regard to the nitrogenous extractive bodies of the muscle in rest and
in activity are likewise uncertain. According to the recent researches
of Monari 2
the total quantity of creatine and creatinine is increased by
work, and indeed the amount of creatinine is especially augmented
by an excess of muscular activity. The creatinine is formed essentially
from the creatine. The investigations of Graham Brown and Cathcart
on removed nerve-muscle preparations of frogs, and those of S. Weber 3
on hearts, indicate an increase in the formation of creatine and creatinine
during work. Weber found that the working heart gave up creatine
(and creatinine) to Ringer’s solution, and indeed much more when
strongly active than during a lesser activity. An increased creatinine
elimination after work does not occur according to several investigators
(see Chapter XIV) and according to Pekelharing and v. Hoogenhuyze
with ordinary muscle activity neither an increased creatine formation
nor an increased creatinine elimination takes place. In the tonic
contraction the creatine is formed from the proteins, and correspond-
ingly according to Pekelharing and Harkink 4
the creatinine elimina-
tion is increased under the influence of the muscle tonus. The purine
bases are produced, according to Burian, in the muscles themselves,
also in activity, and an increased formation takes place during work
due to a re-formation. Scaffidi5
found on the contrary, with frogs and
tortoise, during work that a diminution of the total quantity of purine
bases occurred and indeed not the free but the combined purines.
Attempts have been made to solve the question relative to the
behavior of the nitrogenized constituents of the muscle at rest and during
1
Siegfried, Zeitschr. f. physiol. Chem., 21; Macleod, ibid., 28.
5
Maly’s Jahresber., 19, 296.
» Cathcart and Graham Brown, Journ. of Physiol., 37; Weber, Arch. f. exp. Path,
u. Pharm., 58.
* Pekelharing and v. Hoogenhuyze, Zeitschr. f. physiol. Chem.. 64, with Harkink,
ibid., 75.
6 Burian, Zeitschr. f. physiol. Chem., 43; Scaffidi; Bioch. Zeitschr., 30.
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