Early arteriolar and capillary changes in streptozotocin-induced diabetic rats and intraperitoneal hyperglycaemic rats.

Comparison of intestinal arteriolar characteristics in vivo were made in normal rats, normal rats injected intraperitoneally twice daily with either 0.15 mmol/l saline or 16.6 mmol/l glucose in 0.15 mmol/l saline (total value 5% of body weight), and in streptozotocin treated rats (plasma glucose greater than 22.2 mmol/l). Each regimen was continued for 4-5 weeks before the study. Interperitoneal injection of glucose increased the plasma glucose concentration by 0.8-1.6 mmol/l for 2-2.5 h. The microvascular characteristics of normal and saline injected rats were identical. Results obtained in glucose-treated and diabetic animals were very similar and included: 1) resting arteriolar vasodilation, 2) subnormal dilation at removal of all vascular control with adenosine, 3) total arteriolar vessel wall, including smooth muscle, cross-sectional area and wall to lumen ratio one-third to one-half less than normal, and 4) capillary separation distances increased above normal by 40%-50%. The results indicate that the morphological and functional changes in intestinal arterioles and capillaries found in diabetic rats after 4-5 weeks can be reproduced in the intestinal tissues of a normal animal exposed to intermittent increases in intraperitoneal glucose concentration.