The distribution of calcium and magnesium has been studied in the acinar cells of the pancreas of the guinea pig. Most of the magnesium was found to be associated with the rough microsomes (probably bound to the ribosomes) and with the postmicrosomal supernate. In contrast, calcium was distributed among all the particulate fractions, primarily the mitochondria, microsomes (especially smooth surfaced), zymogen granules, and the plasmalemma, and was low in the postmicrosomal supernate. Most of the calcium recovered in the particulate fractions was found to be membrane bound. The highest concentrations were found in the membranes of the zymogen granules and in the plasmalemma.By means of control experiments using 'sCa as the tracer, it was established that a considerable redistribution of calcium occurs during homogenization and cell fractionation. At least some of the resulting artifacts were estimated quantitatively and the data were corrected accordingly. The biochemical results were confirmed with the cytochemical antimonate technique carried out on the tissue as well as on isolated fractions.The role of calcium associated with the zymogen granules and with their limiting membranes is discussed in relation to the architecture of the granule and to the functionality of the pancreatic juice.It has been clearly established in a number of cell systems that calcium plays an essential role in several steps of the secretory process (I 4). Thus, calcium appears to be involved (a) in the intracellular packaging of secretion products (5, 6), (b) in the regulation of the permeability of the plasmalemma, including the permeability changes occurring after stimulation of secretion (1-4, 7, 8), and (c) in the complex series of events which transduce the stimulation of the secretory cell into its specific secretory response (stimulus-secretion coupling) (1-4, 7 12).Since the pioneer work of Douglas and his associates on the adrenal medulla, the calcium acting in the stimulus-secretion coupling was assumed to be of extracellular origin (9 11). This

SUMMARY Acute ethanol intoxication was studied in 38 Wistar rats, 18 on a balanced dietand 20 on a high fat diet, fed by gavage on 47 % ethanol in a dosage of from 3 to 12 g/kg body weight daily for periods ranging from three to 16 days. No macroscopic changes in pancreas or liver were found in any of these animals. Histological changes (venous congestion of the pancreas, the liver, and the kidneys) were found in rats given 4 g or more per kilogram. The only difference between the findings in rats given a balanced diet and those given a high fat diet was the development of fatty livers in the latter group.Chronic ethanol intoxication was studied in 45 Wistar rats, on a balanced diet, which were given 20% ethanol freely for 20 to 30 months. More than half the animals developed pancreatic lesions very similar to those of human chronic pancreatitis. The pathological changes, in foci surrounded by normal pancreatic tissue, were a reduction in acini, duct multiplication (probably by neogenesis), protein plugs, sometimes calcified in the ducts and sclerosis. Samples of pancreatic juice from four animals exposed to ethanol contained significantly higher protein concentrations than samples taken from two control animals. Protein precipitates appeared spontaneously in the pancreatic juice of the animals exposed to ethanol, but not in that of the controls. These findings are very similar to those in alcoholic pancreatitis in man, which has thus been reproduced for the first time in experimental animals. Beta-cell adenomata of the islets of Langerhans were observed in four of the rats exposed to ethanol.

The high molecular weight (HMW) fibroblast growth factor (FGF)-2 isoform of 210 amino acids initiated at a CUG start codon possesses a nuclear localization sequence and is not secreted. In contrast, the low molecular weight (LMW) isoform of 155 amino acids initiated at the AUG start codon can be secreted and activates the cell surface FGF receptors. The two isoforms possess different biological properties; however, little is known about the intracrine regulatory mechanisms involved in the biological effects of the HMW FGF-2 isoform. Using pancreatic cells stably transfected with cDNAs leading to the expression of either the HMW FGF-2 (A3 cells) or the LMW form (A5 cells), we provide evidence that the two FGF-2 isoforms differentially modulate PKC levels. The LMW FGF-2 up-regulated the PKC ⑀ levels by 1.6-fold; by contrast the HMW isoform down-regulated the level of this PKC isotype by about 3-fold and increased the amount of PKC ␦ by 1.7-fold. PKC mRNAs were also modified, suggesting that PKC expression was regulated at a pretranslational level. Additionally, expression of different levels of the HMW FGF-2 with an inducible expression system confirmed the role of this isoform on PKC ␦ and ⑀ expressions. Increased activation of ERK-1 and -2 was also observed in cells expressing the HMW FGF-2. By using different PKC inhibitors and a dominant negative PKC ␦, it was found that ERK activation was PKC ␦-dependent. These data indicate that expression of HMW FGF-2 can modify PKC levels by acting at the intracellular level and that the overexpression of PKC ␦ induces ERK-1/2 activation. The expression of a dominant negative FGFR1 did not reduce ERK-1/2 activation by the HMW FGF-2, suggesting that ERK activation does not require FGFR activity. The signaling cascade downstream of ERK might be involved in the known mitogenic effect exerted by this FGF-2 isoform.Basic FGF 1 (FGF-2) is a protein belonging to the family of heparin-binding growth factors and is produced by many cell types either normal or malignant (for review see Ref. 1). In tumors, it is one of the key factors regulating growth, blood supply, and invasiveness. These pleiotropic effects have been related to the binding of FGF-2 to high affinity FGF receptors or their splice variants and to low affinity binding sites (2). However, FGF-2 possesses some peculiar features supporting the involvement of other regulatory mechanisms in the final biological effects. Indeed, FGF-2 is synthesized from a single mRNA as five different isoforms with molecular masses of 18, 22, 22.5, 24, and 34 kDa through alternative translation at AUG and CUG start codons (3-5) and through internal ribosomal entries (6). The initiation of translation at the AUG codon gives rise to a peptide of 155 amino acids, and the initiation at the four CUG codons is responsible for the synthesis of the other isoforms that possess N-terminal extensions containing nuclear localization sequences (5, 7). Confocal and immunohistochemical analysis show that these nuclear localization sequence-containing iso...

To evaluate possible functional differences between basic fibroblast growth factor (FGF) 2 isoforms we analyzed the effects of the 18-kDa FGF-2 which mainly localizes in the cytosol and that of the nuclear-targeted 22.5-kDa form on FGF receptors (FGFR) expression. These peptides were expressed at low amounts through a retroviral-infection system. Point mutated FGF-2 cDNAs under the control of the ␤-actin promoter were used to infect a pancreatic cell line (AR4 -2J) which does not produce FGF-2. Saturation and competition binding studies with