On the Non-Ubiquitous Occurrence of Secretin

After Bayliss and Starling found that extracts of the upper intestinal mucosa on intravenous injection would cause the pancreas to secrete, numerous investigators have reported that such an active principle was present in various animal and plant tissues. Such an active principle has been reported to be present in Witte's peptone, stomach and colon mucosa, muscle tissue, brain, thyroid, liver, parathyroids, pineal gland, mammary gland, spinach, nettle, and hydrolized egg-white. All these extracts contain a blood pressure reducing substance; and since histamine increases pancreatic secretion, it may be that the augmentation of pancreatic secretion caused by these various tissue extracts may be due to vaso-dilation and not to a specific substance or secretin.

Having at hand the method of Weaver, Luckhardt and Koch 1 which yields secretin from the upper intestinal mucosa of dogs, hogs, sheep, cattle and man free of vaso-depressor substances, we decided to apply this method to various body tissues and to spinach. The tissues were collected from freshly killed animals, and were cut into small pieces, and 0.4% HCl was added in the proportion of 2000 cc. per kilo of tissue. The acid was allowed to remain in contact with the tissue for 1/2 to 1 hour, with frequent stirring. The acid extract was then strained off through gauze, and immediately saturated with NaCl (30 gm. per 100 cc.), as soon as the salt was dissolved the precipitate was filtered off, the filtrate being called B. The precipitate was then taken up in water and the insoluble residue filtered off and discarded. The soluble portion was called A. The extract A was used for injection. The extracts from the various tissues, brain, bone, liver, lung, kidney, pancreas, thyroid, stomach, intestine, colon, muscle, heart and spinach were injected in doses varying from 5 to 50 cc. No increase in the secretion of the pancreas was noted with any of these tissues except the extract of intestine and stomach.