Dogs with simple gastric fistulas were trained to run in a treadmill. When trained to run without urging or interference, records were taken of the contractions of the empty stomach so as to determine (i) whether muscular activity induces hunger contractions in the quiescent stomach, and (2) whether muscular activity augments the hunger contractions of an active stomach.
The hunger contractions of the stomach of dogs were recorded for 2 to 4 hours after a day's fast, the dogs being taken direct from the kennel without being exercised. On other days the same dogs were taken out for a 4- to 6-mile brisk walk before the 2- to 4-hour recording period.
Records of the gastric hunger contractions were taken with the dog lying quietly in the lap of an assistant. Then the body of the animal was surrounded with an ice pack, or the dog placed directly on a slab of ice. After some training the dogs do not appear much disturbed by the ice pack or slab of ice. The ice pack was applied with the stomach quiescent as well as in hunger activity.
All of these procedures were used on normal dogs and on dogs with the splanchnic nerves sectioned on both sides, in order to have the tonus fibers of the vagi unopposed by the splanchnic inhibitory influence.
The tests were made on the author, on Mr. V. (the gastric fistula case), and on three assistants (J. H. L., S. J. O., A. M. P.).
Records were taken of the gastric hunger and tonus contraction with the man standing or walking or running in situ. Tests were also made after muscular exercise (playing tennis, walking 6 to 12 miles).
The influence of exposure of the body to cold on the gastric hunger mechanism was tested in the following way: (1) While records of the gastric tonus and hunger contractions were being taken, the man, stripped of his clothes, was subjected to cold or warm showers for varying periods. The cold showers were at times sufficiently cold or prolonged to cause intense shivering. (2) The man, stripped of his clothes in a cold room, was covered up on a couch so as to feel comfortably warm. At the desfred moment in the gastric activity, that is, during a period of quiescence or in the midst of a period of hunger contractions, the covers were removed and the cold air of the room set in motion by a fan placed close to the person. This brought on shivering in a few minutes. (3) The man arose at 7:00 a.m. and, without the usual cold bath and breakfast, proceeded to the laboratory, and records of the gastric tonus and hunger contractions were taken from 8:00 a.m. to i 2:00 m. These served as controls. On the other days the man arose at 6:00 a.m., took a cold bath (this was prolonged until the discomfort became very severe), followed by a brisk walk, when records were taken from 8:00 a.m. to 12:00 m.