Functional Microangiopathy in Alloxan Diabetic Rats

Increased capillary permeability can be demonstrated in rats with recently acquired diabetes mellitus induced with alloxan. Alloxan injected non-diabetic rats failed to demonstrate such functional microangiopathology. Diabetic animals were characterized by more rapid transudation of intravenously administered bromphenol blue into intradermal wheals, more rapid loss of radioactive rat serum proteins from the vascular compartment and by the development of gross peripheral oedema or anasarca after intravenous administration of high molecular weight dextran. By contrast, non-diabetic rats, lacking increased vascular permeability, died in acute pulmonary oedema following intravenous colloid overload. It is proposed that functional pathology of the microvasculature characterized by increased capillary permeability may be significantly responsible for the special anatomic changes seen in human diabetic angiopathy.