The Titration Curve of Gastric Mucin

Fogelson 1 has prepared a “gastric mucin” from the gastric mucosa of hogs which has a relatively high combining power for free hydrochloric acid and which has proved to be effective in relieving the symptoms of peptic ulcer when administered in adequate doses. Kim and Ivy 2 have found that the administration of “gastric mucin” prevents the development of duodenal ulcers in biliary fistula dogs. Since Fogelson did not claim that his “gastric mucin” was a pure product, since with his method of preparation, it is very likely that peptone and other products of incomplete protein digestion are present which may account for some of the acid-combining properties of his product, and since we were interested in the mechanism by which “gastric mucin” relieved the symptoms of ulcer and apparently promoted healing, we decided to wash Fogelson's mucin more thoroughly with 60% ethyl alcohol and compare the titration curves of the washed and unwashed “mucins”.

A weighed quantity (50 gm.) of Fogelson's mucin was extracted 4 times with 500 cc. of 60% ethyl alcohol, in which peptone is soluble and mucin is insoluble. It was found that about 60% of Fogel-son's mucin is soluble in 60% ethyl alcohol and 40% is insoluble.

Figure I shows the titration curves of 1 gm. each of Fogelson's gastric mucin (A), the peptone or 60% alcohol soluble fraction (B), the mucin or 60% alcohol insoluble fraction (C), Armour's meat peptone (D), and gelatin (E), in solution in 50 cc. of distilled water. Sufficient sodium hydroxide was added to each solution to give it a pH of 8.0 before the titration with N/10 HCl was started. This was done because it was found that the pH of different batches of Fogelson's mucin obtained from the manufacturing firm (Armour and Co.) varied from pH 7.5 to 8.0.