Secretory oedema in diabetic submandibular glands during parasympathetic nerve stimulation: relationship to microvascular abnormalities in streptozotocin-treated rats.

1. Submandibular secretion during parasympathetic stimulation (5 Hz) was examined in streptozotocin-diabetic and age-matched control rats. 2. At 3 weeks, but not 3 and 6 months, flow rate was initially greater than in controls, but it declined rapidly after 30 min. 3. The reduction in flow rate was associated with oedema of the gland. 4. At 3 months, graded stimulation revealed a tendency to oedema at frequencies of 10 Hz and above. 5. Morphologically, submandibular capillary density was increased in diabetic rats. 6. Thus, in diabetes the submandibular gland appears less able to withstand continuous parasympathetic stimulation, due in part to an increase in tissue capillary area.