POSSIBLE RELATIONSHIP BETWEEN INCREASED BETA-CELL VOLUME AND INSULIN-SECRETION

We propose a speculative hypothesis that increased pancreatic beta-cell volume is involved in the mechanism of insulin secretion. Parallels between effects on liver glycogen synthesis and pancreatic insulin secretion are described. High medium K+, agents which decrease K+ conductance, amino acids and their analogues increase both processes while high medium Zn2+ strongly inhibits both processes. We propose that part of the mechanism of action of the diverse metabolic secretagogues such as D-glucose, D-glyceraldehyde, L-leucine and monomethyl succinate involves organic acid production, which when coupled primarily to Na+/H+ countertransport, and other countertransports, leads to the production of osmotically active solutes (ultimately K+HCO3- or K+Cl-), and a-degree of cell swelling. Cell growth might also involve an increased cell volume trigger mechanism, and metabolism could also contribute to this signal.