Full resolution (JPEG) - On this page / på denna sida - X. The Muscles - Striated Muscles - Proteins of the Muscles
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5€6 MUSCLES.
If the muscular fibers are treated with reagents which dissolve proteins,
such as dilute hydrochloric acid, soda solution, or gastric juice, they swell greatly
and break up into " Bowman’s disks." By the action of alcohol, chromic acid,
boiling water, or in general such reagents as cause a shrinking, the fibers split
longitudinally into fibrils; and this behavior shows that several chemically dif-
ferent substances of various solubilities enter into the construction of the muscular
fibers.
The protein myosin is generally considered as the principal constituent of the
diagonal disks, while the isotropous substance contains the chief mass of the
other proteins of the muscles as well as the chief portion of the extractives.
According to the observations of Danilewsky, confirmed by J. Holmgren, 1
myosin may be completely extracted from the muscle without changing its struc-
ture, by means of a 5-per cent solution of ammonium chloride, which fact con-
flicts with the above view. Danilewsky claims that another protein-like sub-
stance, insoluble in ammonium chloride and only swelling up therein, enters essen-
tially into the structure of the muscles. The proteins, which form^the principal
part of the solids of the muscles, are of the greatest importance.
Proteins of the Muscles.
Like the blood which contains a fluid, the blood-plasma, which sponta-
neously coagulates, separating fibrin and yielding blood-serum, so also
the living muscle, at least of cold-blooded animals, contains, as first
shown by Kuhne, a spontaneously coagulating liquid, the muscle-plasma,
which coagulates quickly, separating a protein body, myosin, and yield-
ing also a serum. That liquid which is obtained by pressing the living
muicle is called muscle-plasma, while that obtained from the dead
muscle is called muscle-serum. These two fluids contain at least in part
different protein bodies.
Muscle-plasma was first prepared by Kuhne from frog-muscles, and later
by Halliburton, according to the same method, from the muscles of warm-
blooded animals, especially rabbits. The principle of this method is as follows:
The blood is removed from the muscles immediately after the death of the animal
by passing through them a strongly cooled common-salt solution of 5-6 p. m.
Then the muscles are quickly cut and immediately frozen thoroughly so that
they can be ground in this state to a fine mass—" muscle-snow." This pulp is
strongly pressed in the cold, and the liquid which exudes is called muscle-plasma.
According to v. Furth 2
this cooling or freezing is not necessary. It is sufficient
to extract the muscle free from blood, as above directed, with a 6 p. m. common
salt solution.
Muscle-plasma forms a yellow to brownish-colored fluid with an
alkaline reaction. It varies in different animals. Muscle-plasma from
the frog spontaneously coagulates, slowly, at a little above 0° C, but more
1
Danilewsky, Zeitschr. f. physiol. Chem., 7; J. Holmgren, Maly’s Jahresber., 23.
2
See Kuhne, Untersuchungen iiber das Protoplasma, (Leipzig, 1864), 2; Hallibur-
ton, Journ. of Physiol., 8; v. Furth, Arch. f. exp. Path. u. Pharm., 36 and 37; Hof-
meister’s Beftrage, 3, and Ergebnisse der Physiologie, 1, Abt. 1; Stewart and Soll-
mann, Journ. of Physiol., 24.
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