* The digestive time was kept constant at fifteen minutes. (The gastric juice used had been diluted with stomach washings.)
The reader will observe in Table 1 that the results obtained from the control injection of secretin at the beginning of the experiment is uniformly greater than that obtained after several injections of digested secretin.
In view of the established fact that equal quantities of secretin can generally be relied on to produce results,[62] one might suggest that the injections of the split products of secretin have inhibited to some degree the action of the pancreas. We can submit the data in Table 3 in support of this view, showing among other things that the action of secretin is not influenced by previous injections of inert depressor substances, though it by the injection of the cleavage products of secretin. (The various injections in the experiments were made at about fifteen-minute intervals).
We have carefully analyzed the reaction in blood pressure that follows the injection of the various preparations. We find no constant effect. Digested secretin gives a fall in blood pressure that is at times less, at times equal, and at other times greater (Fig. 1) than that produced by the original preparation.
Besides the bearing that it has on the therapeutic use of secretin, this destructive action of the digestive enzymes is also of prime physiologic interest. Failure to realize it has led to misconceptions as to the intrinsic nature of secretin.
TABLE 3.—EXPERIMENTS 8 AND 9
| Preparation | Pancreatic Juice Drops |
| Experiment 8: | |
10 c.c. secretin, five injections of inert depressor substances | 29 |
10 c.c. secretin, two injections of completely digested secretin | 28 |
10 c.c. secretin, eight injections of inert depressor substances | 16 |
10 c.c. secretin | 16 |
| Experiment 9: | |
10 c.c. secretin (control, beginning of experiment) | 21 |
| 10 c.c. secretin, after thirty minutes incubation with 1 c.c. | |
boiled gastric juice | 27 |
| 10 c.c. secretin, after thirty minutes incubation with 1 c.c. | |
fresh gastric juice | 11 |
10 c.c. secretin (control, end of experiment) | 18 |
The findings of Lalou, confirmed by us, explain the anomaly that has led Delezenne[88] to put forward the antisecretin theory.