Further experiments making injections into both the lumbar and the
gluteal muscles, were made in this series.
_Rabbit 577. Gray male. Weight, 1,380 grams._
February 14: 3 p. m. 14 cc 2 per cent caffein injected into the gluteal
muscles of the right side; 3.10 p. m., restless, jumped off the table
and walked about, reflexes increased; 3.45 p. m., passed 30 cc clear,
straw-colored urine; 4.45 p. m., allowed to walk about, ran across the
room, about 20 feet, looked tired, stretched himself out on the floor,
then raised himself and walked about showing no disturbance of gait.
February 15: 9 a. m., found dead.
_Rabbit 578. Gray, female. Weight, 1,670 grams._
February 14: 3.05 p. m., 18 cc 2 per cent caffein solution injected
into the gluteal muscles of the right side; 3.15 reflexes increased,
but not restless; 5 p. m., allowed to walk about, no symptoms observed.
February 15: Found dead.
_Rabbit 579. White and gray, male. Weight, 1,490 grams._
February 14: 3.15 p. m., 15 cc 2 per cent caffein solution injected
into the gluteal muscles of the right side; put in cage; 3.30 p. m.,
reflexes increased; 5 p. m., taken out of cage and allowed to walk
across the room, no special symptoms noticed.
February 23: Still alive.
_Rabbit 580. Gray male. Weight, 1,510 grams._
February 14: 3.35 p. m., 15 cc 2 per cent caffein solution injected
into lumbar muscles.
February 23: Still alive, in good condition.
_Rabbit 581. Gray female. Weight, 1,680 grams._
February 14: 3.45 p. m., 17 cc 2 per cent caffein solution injected
into the lumbar muscles of the right side; 4 p. m., reflexes increased;
4.15 p. m., jumped off the table and had wild convulsions, became very
restless, walked about the laboratory; 4.25 p. m., had convulsions
occasionally; 4.30 p. m., extremities extended and quite rigid;
4.35 p. m., convulsions and death.
_Rabbit 582. Gray male. Weight, 1,870 grams._
February 14: 4.15 p. m., 18 cc 2 per cent caffein solution injected
into the lumbar muscles of right side; 5 p. m., reflexes increased;
walked about in the room, then rested; 5.15 p. m., had short spasm when
handled.
February 23: Alive; good condition.
The data presented in these experiments show that the toxicity of
caffein when injected into the muscles of the lumbar regions is the
same as when injected into the gluteal muscles. The rabbits of series
A received approximately 0.2 gram caffein per kilo and two died as
a result of this treatment. The other two survived but symptoms of
caffein intoxication were observed.
In series B smaller doses proved fatal, from which it would appear
that caffein is more toxic when injected into the lumbar muscles.
Further observations, however, failed to corroborate the results
obtained in this series. Thus, in series C, 130 to 150 mg of caffein
per kilo injected into the lumbar muscles produced mild symptoms
only. Experiments with larger doses showed that 0.180 gram caffein
per kilo may cause death. It will be noticed, on the other hand, that
rabbit No. 455 survived a dose of 0.2 gram per kilo. New experiments
were therefore carried out in which the same amounts of caffein in
proportion to the weight of the animals were injected into the lumbar
muscles as into the gluteal muscles. As shown in the experiments of
series D, one rabbit (No. 581) died shortly after caffein was injected
into the lumbar muscles; two recovered. Two of the three which received
injections into the gluteal muscles were found dead the next day; one
recovered. Post-mortem examination failed to indicate the presence
of any abnormalities. The rate of absorption of caffein from the
gluteal and from the lumbar muscles seems to be, therefore, the same,
or not to differ very much. The observations of Auer and Meltzer(7)
are of interest in this connection. According to their investigations
adrenalin is more rapidly absorbed from the lumbar than from the
gluteal muscles. This is in all probability due to the greater delicacy
of the test they employed (since they judged the rate of absorption
by the effect of adrenalin on blood pressure) as well as to the much
greater activity of the substance.