Pepsinogen secretion from perifused frog peptic glands: rapid transients detected with a modified pepsin assay.
In order to define the early transient responses of peptic cells to stimulation, we have modified the acidified hemoglobin substrate digestion method for pepsin to provide a very sensitive, linear (10-250 ng/ml), reproducible, inexpensive (less than 3 cents/sample) and simple semi-automated assay. Using a specially designed perifusion chamber, this method was used to accurately measure secretion at 1 min intervals from approximately 3 mg of isolated peptic glands from the esophageal peptic organ of R. catesbeiana, containing approximately 150 micrograms pepsinogen. Responses to carbachol applied for 1, 2 and 4 min could be described in discrete 1 min intervals. Secretion stimulated by carbachol (1-2 min) peaked at 200-300% of basal and upon withdrawal decayed with t1/2 approximately 3 min. Atropine added to continuous carbachol stimulation inhibited secretion with t1/2 approximately 4 min, indicating rapid metabolism of activated messengers.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D004947:Esophagus / Q000187:drug effects / Q000378:metabolism*; D006454:Hemoglobins / Q000378:metabolism; D066298:In Vitro Techniques; D009092:Mucous Membrane / Q000378:metabolism*; D010434:Pepsin A / Q000032:analysis*; D010435:Pepsinogens / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010477:Perfusion / Q000379:methods; D011892:Rana catesbeiana; D014443:Tyrosine / Q000032:analysis
D006454:Hemoglobins; D010435:Pepsinogens; D014443:Tyrosine; D001285:Atropine; D002217:Carbachol; D010434:Pepsin A