Decreased vascular reactions to permeability factors in experimental diabetes.

Light and electron microscopic studies showed that blood vessels of the cremaster muscle of alloxan-diabetic rats under the local influence of histamine or serotonin presented less labelling by colloidal carbon, previously injected i.v., than vessels of normal rats. The hyporeactive state of these vessels was promptly reversed to normal conditions by the administration of insulin. Insulin also potentiated leakage of carbon particles in the vessels of normal animals. These findings add new evidence that insulin might be involved in vascular events following injury and that decreased levels of the hormone, as occurring in diabetes, might result in decreased inflammatory reactions.