Structural and Functional Characterization of Isolated Pancreatic Exocrine Cells

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Abstract
Viable isolated exocrine cells have been obtained from guinea-pig pancreas by a tissue dissociation procedure using crude collagenase (EC 3.4.4.19) and hyaluronidase (EC 3.2.1.35), chelation of divalent cations, and mild shearing forces. Cell yields are 50-60%, based on recovered DNA, and about 90% of the population consists of exocrine cells which, although rounded up, retain their in situ polarity with regard to regional distribution of zymogen granules and specialization of the former luminal plasmalemma. The isolated cells incorporate labeled amino acids into proteins at linear rates for at least 4 hr at levels comparable to pancreatic slices in vitro; more than 95% of the exocrine cell population is active in this process, as shown by autoradiography. In response to secretogogues at optimal doses (100 muM carbamylcholine; 0.1 muM pancreozymin, or 0.01 muM caerulein), the cells discharge up to 30% of their content of pulse-labeled secretory proteins to the medium over a 3-hr period; in the same time, the controls release about 5% of their content. The results indicate that isolated exocrine cells are capable of synthesizing the processing secretory proteins, and of responding directly to cholinergic and peptidic secretogogues.