Intestinal microvascular growth during maturation in diabetic juvenile rats.

To determine if intestinal microvascular growth is impaired in diabetic juvenile animals, a segment of the terminal ileum was marked and the microvasculature of this segment observed at the age of 5 weeks and again at the age of 10-11 weeks in normal and diabetic Sprague Dawley rats. Diabetes was induced by streptozotocin after the first observation period and the plasma glucose concentration exceeded 500 mg% by the age of 10-11 weeks. Microvascular growth was quantitated by measurements of the number, length, and maximally dilated inner diameters of specific arterioles and by intercapillary distances in the marked intestinal region at both ages. Although intestinal enlargement was much greater in diabetics, there was no change in the number of arterioles during maturation and intercapillary distances were equivalent in diabetic and normal rats. In normal and diabetic animals, the arteriolar length increased to match bowel elongation, however, increases in bowel and arteriolar lengths in diabetic animals were about twice that of normal rats. During juvenile maturation, the maximally dilated inner diameters of the small arterioles in diabetic animals were increased compared with their normal counterparts. Thus, arteriolar growth during maturation is characterized by changes in the length but not in the number of vessels in intestine of both normal and diabetic rats. The perfusion of about 90% more tissue by mass for each arteriole in diabetic rats is facilitated by arteriolar dilation.(ABSTRACT TRUNCATED AT 250 WORDS)