Changes in the Size of the Spleen Following Exercise.

Abstract

Barcroft and Stephens 1 in a recent investigation have shown that gross changes in the size of the mammalian spleen may be studied in so called exteriorized preparations by means of outline tracings on a plate of celluloid. They find that during muscular activity the spleen shrinks to approximately two-thirds of its resting area.

It seemed worth while to us to investigate the course of recovery in the size of spleens which had contracted as a result of periods of exercise of widely varying intensity and duration. The technique of our experiments differed from that of the Cambridge workers in that we were making recovery observations over short periods of time on decerebrate cats, exercised by means of electrical stimulation. Hence it was sufficient to make a temporary exteriorization which consisted essentially of bringing the spleen through a 2 inch incision which had been carried from the skin through the peritoneum. During active exercise and when no actual measurements were being made, the spleen was returned to its place in the abdomen, and the incision was temporarily closed. Control experiments showed that this repeated exteriorization and replacement per se had no apparent effect on size. The area of the spleen was computed from the tracings and used as a basis of comparison.

The results of our experiments show that in cats which were decerebrated so that no rigidity developed, the spleen immediately after exercise had contracted to about 70% of its original area; the latter had teen determined before exercise. Our experiments on this point thus check with those of Barcroft and Stephens within reasonable limits.

Having measured the extreme contraction immediately after exercise, we then traced the course of recovery by continuing measurements until the spleen had attained all or most of its resting size. We found that recovery begins as soon as the exercise ceases because our measurements (made within 1 minute of the cessation of the electrical stimulation) invariably show a spleen which is increasing in size. This increase appears to consist of 2 phases, of which the first is very rapid, particularly within the first 5 minutes.