SECRETORY AND SYNTHETIC CHANGES IN THE SECRETORY PROTEINASES OF MOUSESUBMANDIBULAR GLANDS AFTER METHOXAMINE STIMULATION, ASSESSED HISTOCHEMICALLY BY MEANS OF D-VAL-LEU-ARG-METHOXY-NAPHTHYLAMIDE

The secretion of proteinases and their resynthesis in the granular con voluted tubule (GCT) cells of mouse submandibular glands were studied after in vivo methoxamine (Methox) treatment (15 mg/kg, i. p.), using a histochemical reaction with D-Val-Leu-Arg-4-methoxy-2-naphthylamide. The amidase reaction product was confined to the secretory granules i n GCT cells, in unstimulated and stimulated glands. Methox caused exte nsive secretion of the granules. An increased staining reaction by the proteinases seemed to occur in granules prior to secretion, and fusio ns had often taken place. Reaccumulation of proteinases in the newly f orming granules was found to start between 6 to 12 hr after injection and the process was still incomplete at 48 hr, but the granules showed less staining than at the earlier times. The variations observed in s taining intensity may relate to the extent of binding with other prote ins, and an unbinding of proteinases appears to be a possibility prior to the secretion of granules.