DEFECTIVE CYTOPLASMIC GRANULE FORMATION II - DIFFERENCES IN PATTERNS OF RADIOLABELING OF SECRETORY GRANULES IN BEIGE VERSUS NORMAL MOUSE PANCREATIC ACINAR-CELLS AFTER [H-3]GLYCINE ADMINISTRATION IN-VIVO

We investigated the development of secretory granules in the pancreati c acinar cells of normal (C57BL/6J +/+) and beige (C57BL/6J Lyst(bg)/L yst(bg)) mice by analyzing the distribution of H-3 label in pancreatic acinar cells after a pulse of [H-3]glycine administered in vivo. The results provide quantitative confirmation of the hypothesis that the m aturation of condensing vacuoles/immature granules to mature granules in pancreatic acinar cells is associated with a significant volume red uction. Beige mice differ from control mice by exhibiting a more rapid distribution of H-3 label from the rough endoplasmic reticulum-rich c ytoplasm to the secretory granules and a slightly faster rate of matur ation of H-3-labeled granules. Beige mouse pancreatic acinar cells als o exhibited, as early as 1 h after pulsing with [H-3]glycine, a much h igher proportion of H-3-labeled secretory granules than did the cells of control mice. These findings identify additional abnormalities in s ecretory granule formation in pancreatic acinar cells which are relate d to the beige (Lyst(bg)) mutation and provide support for the hypothe sis that beige mice exhibit an abnormal pattern of granule-granule fus ion.