Localization and possible function of polyamines in protein and peptide secreting cells

Three different cytochemical methods, the formaldehyde-fluorescamine and the ortho-phtalaldehyde fluorescence cytochemical methods as well as immunocytochemistry have been developed for localising the polyamines spermidine and spermine in tissue. All three methods produce identical results and show polyamines to occur inter alia in high concentrations in certain protein- and peptide-secreting cells. Many of these cells also show the capacity to metabolise monoamines and belong to the amine content or amine precursor uptake and decarboxylation (APUD) series. In cell types where fluorescence microscopical resolution allows, most polyamines appear to be localised to secretory granules. Moreover, studies on isolated pancreatic islets reveal active and glucose-dependent polyamine biosynthesis to occur in insulin cells. Possible function of polyamines in secretory granules are discussed in the light of the above findings.