Gene amplification in multidrug-resistant cells: molecular and karyotypic events

The two theories of pancreatic enzyme secretion, those of exocytosis and transmembrane flow, are described. Data thought to support the theory of transmembrane flow of single molecules from pancreatic acinar cells are first reviewed, and the conditions which could allow these data to be explained by the theory of exocytosis of enzyme quanta, i.e. secretory granules, are then discussed. The evidence suggesting short-term modulation of the composition of pancreatic juice is also considered, and its possible explanations at the organ and cellular level are discussed, in the light of suggested theories on enzyme secretion pathways.