The Local Application of Saline Solutions to the Peritoneal Surfaces of
the Intestine.
In the last chapter it has been shown that the subcutaneous and
intravenous injections of solutions of various saline purgatives
produce a characteristic purgative effect; and that similar injections
of calcium or magnesium chloride inhibit this action and bring the
intestines to rest.
I have found also that solutions of these salts have the same effect
when applied directly to the peritoneal surface of the intestine. Thus
if a solution of sodium citrate or sulphate,[31] for example, be poured
over the intestine those loops which are moistened by the solution will
become active within one minute. After a very short time the remaining
loops are also set in motion. These movements may be entirely inhibited
by pouring on the loops a solution of calcium or magnesium chloride.
The following description of these experiments is taken directly from
my paper which appeared two years ago.[32]
The intestines of a rabbit under the influence of morphine were
exposed. On a small group of coils there were poured 3 c.c. m/6 sodium
citrate solution. Almost immediately (within 1 minute) the loops became
very active. Strong contractions of the muscle coats took place. After
a few minutes the other loops were also set in movement, so that the
whole small intestine showed active peristalsis. The citrate solution
was then washed off by m/6 NaCl solution, and about 3 c.c. m/6 CaCl_{2}
solution poured on the loops. The peristaltic movements were promptly
suppressed, and the intestine remained quiet. By the further addition
of citrate solution, the coils were set in active movement once more,
and by the subsequent application of calcium chloride solution again
inhibited. This was repeated many times (sixteen) and apparently might
have been continued as long as the intestine remained alive.
The same results were obtained by using instead of the sodium citrate
solution, a solution of barium chloride, sodium sulphate, fluoride,
bromide, iodide, phosphate (Na_{3}PO_{4}), oxalate or tartrate. Local
application of solutions of any of these salts produces increased
peristaltic activity. Solutions of sodium chloride have a very slight
action of the same character. On the other hand, the intestinal
movements are equally inhibited by calcium chloride and magnesium
chloride, while strontium chloride has a similar but less powerful
inhibiting action.
In testing those salts with which it was necessary to use dilutions
greater than m/8, the dilution was made with a neutral fluid consisting
of sodium chloride and magnesium chloride. It was found that m/6 NaCl
solution increased to a very slight extent the peristaltic movements.
By adding to 10 c.c. m/6 NaCl, 0.5 c.c. m/6 MgCl_{2}, a fluid was
obtained which had apparently neither stimulating nor inhibiting
effects. In addition to solutions made up by dilution with this neutral
fluid, others were used in which the salt solutions were diluted with
distilled water. Practically the same results were obtained in both
cases. It was found that 1 c.c. m/320 BaCl_{2} solution applied locally
to the intestine is sufficient to cause strong peristaltic movements in
a rabbit. This quantity contains about 0.00076 gm. barium chloride.
In the case of sodium citrate, the concentration must be considerably
greater. No solution of this salt more dilute than m/80 is active in a
rabbit. Of all the purgative salts, barium chloride is by far the most
powerful. If a drop of m/8 BaCl_{2} be placed on the serous surface of
an intestinal loop, or if a small area be moistened with this solution
by means of a camel’s hair brush, the muscle beneath the moistened
area will almost immediately contract so that a ring-like constriction
of the intestine is formed. This often is so sharply marked that it
suggests the effect produced by tying a ligature around the intestine.
This constriction remains for a few moments, and then gradually moves
along the loop in the direction of the normal peristalsis. If the
solution be injected into the muscle of the intestine at any point
with a hypodermic needle, a similar sharp constriction takes place. If
also a few drops be injected directly into a branch of the superior
mesenteric artery, all that part of the loop supplied by the arterial
branch will contract violently. These statements are true also in the
case of sodium citrate, fluoride, sulphate, etc.; the action of these
salts, however, is less powerful.
It must be added here also that the actual passage of faeces may be
produced within an hour by the application of the purgative salts to
the serous surfaces of the intestine. This takes place most quickly
with barium chloride. It is possible to observe directly through the
semi-transparent walls of the intestine the rapid passage of faecal
masses from one loop to another.
The intestines of the rabbit are apparently much more sensitive to the
action of sodium citrate and sulphate than are those of the dog or
cat. Barium chloride, on the contrary, acts with equal strength in all
these animals. In a rabbit, the intestines are always set in active
peristaltic movement by contact with m/8 sodium citrate solution;
and even much more dilute solutions are, as a rule, effective. In a
cat, however, it was found that an m/8 solution of sodium citrate
has practically no effect, while a ⁵⁄₈m solution sets the intestine
in active motion. In a dog also m/8 sodium citrate solution is
usually ineffective. Similarly an m/8 sodium sulphate solution is
inactive in a dog while an m/2 solution of the same salt starts up
distinct peristalsis. In the cat and dog also the peristalsis may be
inhibited by calcium or magnesium chloride, as shown in the following
experiments. The intestines of a cat were exposed in the usual manner,
and an m/8 solution of sodium citrate was applied to the serous surface
of the loops. There was no increased movement. There were then poured
on the loops a few cubic centimetres of a mixture of 5 c.c. ⁵⁄₈m sodium
citrate and 5 c.c. ⁵⁄₈m CaCl_{2}. The loops remained motionless.
After waiting a considerable time (15 minutes), a ⁵⁄₈m solution of
sodium citrate alone was poured on the intestine. Almost immediately
they became very active; and the peristalsis continued until calcium
chloride was again applied. The loops then came to a standstill. The
difference in susceptibility to the action of citrate which exists
between rabbits on the one hand, and dogs and cats on the other, may
be in some way connected with their being herbivorous and carnivorous
animals respectively.
The action of the sodium citrate, sulphate, fluoride, etc., when
applied locally, may be inhibited by the administration of an
approximately equal quantity of calcium or magnesium chloride of
the same concentration. The counteraction of the effect of barium
chloride, however, requires a much greater concentration of calcium.
Using equal quantities of the two salts, the action of the barium is
usually not inhibited, a fact which I have previously stated. With
greater concentrations of the calcium chloride, the antagonistic
action, however, is clear. This is shown in the following experiment:
Applied locally to the intestine of a rabbit 1 c.c. m/320 BaCl_{2}
solution caused active peristaltic movements. The application of 1
c.c. m/320 CaCl_{2} solution exercised no inhibiting effect whatever.
The same quantity of m/40 CaCl_{2} was then poured on the loops, and
a slight but distinct quieting of the loops took place. The addition
of 1 c.c. m/6 CaCl_{2} caused the loops to become entirely motionless.
After waiting a considerable time, 1 c.c. m/8 BaCl_{2} was poured
on the intestine. Immediately violent peristaltic movements took
place. Several c.c. m/6 CaCl_{2} exercised practically no inhibiting
influence; while 2 c.c. ⁵⁄₈m CaCl_{2} solution suppressed the movements
entirely for a short time.
The question concerning the exact seat of action of the purgative
salts remains still unanswered. Whether, upon being absorbed into the
blood, they act on the central nervous system is not known. There is
no evidence to show that this is the case. It seems certain, on the
other hand, from the experiments here described, that they undoubtedly
have a peripheral action either on the peripheral nervous mechanism or
on the muscle cells themselves. It is impossible to prove that there
is no action on the central nervous system, and at present it seems
impossible to prove whether the peripheral action is directly on the
nerves or on the muscles. The existence in the walls of the intestine
of the ganglionic plexuses of Auerbach and Meissner must be taken
into consideration; and with the methods available there seems to be
no way of distinguishing the action on these plexuses and the direct
action on the muscle cells. The ultimate effect is on the muscles and
glands; and the fact that an entirely local ring-shaped constriction
can be brought about by the local application of a drop of one of the
salt solutions to the surface of the intestine would seem to indicate
that only a small group of the circular muscle fibres themselves is
affected. The fact that the nerve plexuses form a continuous network,
and are intimately related in their various parts, would suggest that
the occurrence of an action on these plexuses confined to so small an
area is improbable. The discussion of the exact location of the action
is, however, of relatively little importance, as compared with the
main facts shown by these experiments, namely, that _it is possible to
produce, by the local application of a purgative salt to the serous
surface of the intestine, a striking increase in peristalsis, and to
suppress these movements by a similar application of solutions of
calcium, magnesium, or strontium chloride_.
These experiments also seem to decide the question as to whether the
salt solutions act after being absorbed into the blood or only when
placed in the intestine. According to Hay[33] and others, the salt
which is absorbed into the circulation has no effect and the only
action is produced by that which remains in the intestine. This is
obviously not true since the solutions act much more rapidly and more
powerfully when applied to the outside of the intestine, _i.e._, to
the peritoneal surface. No action is observed until after an interval
of 10 to 15 minutes after the salt solution is placed in the lumen of
the intestine, while application of the same solution to the peritoneal
surface causes movements of the intestine within one minute.
FOOTNOTES:
[31] Pohl (Arch. f. exp. Path. u. Pharm., Bd. 34, S. 87) stated that
all sodium and ammonium salts increased the peristalsis when applied to
the peritoneal surface of the intestine.
[32] MACCALLUM, J. B.: Amer. Journ. Physiol., Vol. X, No. V, 1904, p.
259.
[33] _Loc. cit._