Cytological Studies on the Cause of Pancreatic Secretion. II

Abstract

It is suggested, from earlier studies on the functional changes of pancreatic cells, that the factor causing secretion of secretin from the mucous membrane of the duodenum when food is given orally, is “HCL+X”, and that this X must be a peculiar substance and may be effected by the quality of food. In order to prove the existence of this X, HCL (0.4%), protein (casein) and fat (sesame oil) were injected separately into the lumen of rat's duodenum, and the functional changes of the minute structure of pancreatic cells were observed.When HCL, casein and sesame oil are injected separately, pancreatic cells show but a slight discharge of granules, and the discharge pictures are similar in all three cases, the quality oh the substance having no special effect.When HCL is added to casein or sesame oil, a very strong discharge occurs soon after the injection and continues for 2 hours in the case of casein and 60 minutes in the case of sesame oil. The functional pictures are the same as. with oral administration of casein or sesame oil.Casein and artificfal gastric juice produce a slighter discharge than casein added with HCL, and moreover it only continues foi 60 minutes. It is believed that this is a result of the partial breakdown of casein by pepsin. When sesame oil and artificial gastric juice are injected, the picture. is quite similar to that of sesame oil and HCL.As shown by these results it is clear that the factor which causes secretion of secretin from the mucous membrane of the duodenum is not HCL, protein or fat alone, but a mixture of protein or fat with HCL. The fact that there is a difference in functional picture between “casein and HCL” and “sesame oil and HCL” is sufficient to show that X which differs with the substance exists in conjunction with HCL.On the other hand the production of zymogen granules (which are presumably the transformation of plastosomes) is in the case of duodenal injectin of the above-stateds ubstances too slight to be of question when compared to oral administration of them. All these facts show positively that the two functions of the pancreatic cells, i. e. discharging and producing of zymogen granules, are initiated by separate stimuli.