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496 DIGESTION.
During starvation the secretion almost stops, but commences again
after partaking of food and reaches its maximum, it is claimed by
Bernstein, Heidenhain, and others, within the first three hours.
Pawlow and his pupils, especially Schepowalnikoff, have shown
that the above-mentioned (page 492) enterokinase activates the trypsino-
gen into trypsin. These observations were later confirmed by others,
by Delezenne and Frouin, Popielski, Camus and Gley, Bayliss and
Starling, Zunz, and have been further studied. The pure juice con-
tains, at least as a rule, only trypsinogen, and no trypsin. By mixing
with the intestinal juice, or by contact with the intestinal mucosa, the
trypsinogen is converted into trypsin by the kinase. Enterokinase,
which itself has no action upon proteins, and therefore is not a pro-
teolytic enzyme, is not well known. It is made inactive by heating and
is therefore considered by many (including Pawlow) as an enzyme.
Others, on the contrary, like Hamburger and Hekma, Dastre and
Stassano, deny the enzyme nature of enterokinase because they find
that a certain quantity of intestinal juice will activate only a certain
quantity of trypsin. Enterokinase has been found in man and all
mammals investigated. According to most investigators it is formed
in the glands or the cells of the intestinal mucosa, while according to
Delezenne it comes from Peyer’s patches and from the lymph-glands
and leucocytes, hence impure fibrin containing leucocytes acts as a kin-
ase. These deductions of Delezenne are disputed by Bayliss and"
Starling, Hekma and others.
If we accept the view that the juice secreted after partaking food
is regularly free from trypsin, still under other circumstances the juice
may contain trypsin. Thus, according to Camus and Gley, the juice
secreted under the influence of secretin (see below) is not always free
from trypsin, and Zunz found that Witte’s peptone or pilocarpine
causes a secretion of juice which often contained trypsin and was directly
active. According to Camus and Gley not only does an exterior activa-
tion of the trypsinogen in the juice take place, but also in the interior
of the gland. An auto-activation of the juice in certain cases is also
accepted by others (Sawitsch 1
).
The activation of the trypsinogen into trypsin may, in life, be brought about
—as the researches of Herzen, which have been substantiated by Gachet and
Pachon, Bellamy, Mendel and Rettger, have shown—not only in the intestine,
but also in the gland itself. This activation of the trypsinogen in the gland itself
is caused in a still undiscovered manner by a body of unknown nature formed in the
spleen, which is congested during digestion. Such a " charging " of the pancreas
1
Camus and Gley, Journ. de Physiol, et de Pathol, gem, 1907; Zunz, Recherches
sur l’activation de sac pancreatique par les Sels., Bruxelles, 1907; Sawitsch, Zentralbl.
f. d. ges. Physiol, u. Path, des Stoffwechsels, 1909.
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