Endosomal proteins are lost during in vivo and in vitro pancreatitis. Isolated rat pancreatic acini were left untreated or stimulated with supramax CCK-8 (100 nm) for 60 min. A, whole cell lysates were immunoblotted for pancreatic lipase and endosomal proteins (D52, EEA1, Rab5). Immunoblots were quantified and plotted as the -fold of untreated levels indicated by the dashed line (data are the mean and S.E. *, p < 0.05). All experiments were generated from at least three separate acinar preparations, performed in duplicate. B and C, pancreatitis was induced in rats by a single IV injection of supramximal CR (50 μg/kg of body weight) or saline control. 1-h post injection the indicated protein (B) and mRNA (C) levels were analyzed in pancreatic homogenates. Data are the mean and S.E., n = 3–4 animals per group. D, endosomal protein (D52, EEA1, Rab5) expression was analyzed after induction of in vivo pancreatitis in mice given 7 hourly IP injections of CR or after 72 h feeding of a choline-deficient/ethionine-supplemented diet (CDE). E, endosomal protein (D52, EEA1, Rab5) expression after induction of in vivo pancreatitis in rats given 4 hourly i.p. injections of CR. Note that after 1-h CR pancreatitis in vivo (panel B), although all endosomal proteins were reduced, only D52 and EEA1 were significant (p < 0.05); however, at longer periods in both rat and mouse (panels D and E, respectively) all endosomal proteins are markedly reduced.