Male Wistar rats were fasted overnight and anaesthetized 3-4 weeks after the induction of streptozotocin diabetes. The right parotid ducts were cannulated, and parotid salivary flow was induced by stimulating the sympathetic trunk in bursts (50 Hz, 1:10). Stimulated and unstimulated glands were weighed, fixed for morphometric analysis, and assayed for total protein and amylase. Gland weights did not differ between diabetic and control rats. Nevertheless, total protein (6.17 +/- 5.40 mg) and amylase (1.32 +/- 0.49 mg) output from the gland were reduced in diabetic animals compared with controls (13.73 +/- 2.81 and 3.41 +/- 0.51 mg, respectively). Morphometric analysis of unstimulated glands showed no differences in either acinar cell profile area, or in the number of secretory granule profiles/cell in unstimulated glands. Upon sympathetic stimulation, however, the depletion of granule profiles was significantly less in diabetic than in control rats. Finally, the mean diameter of secretory granules was significantly less in diabetic (0.89 +/- 0.05 microM) than in control (1.04 +/- 0.06 microM) glands.