The use of radioactive microspheres to quantitate hyperemia in dermal inflammatory sites.

A variety of dermal lesions produced by PGE1, tuberculin, and allogeneic lymphocytes were induced in rabbits, guinea pigs, and sheep, respectively. Microspheres labeled with 85Sr were injected into the ascending aorta, and the distribution of radioactivity in the lesions, saline control sites, and various major organs was assessed. It was concluded that the trapping of the microspheres was related to the degree of hyperemia induced, and that this technique enabled a quantitative measure of the blood flow. PGE1 was found to be a potent mediator of hyperemia and to have a significant effect on the blood flow at a dose of 1 ng. The blood flow to cellular hypersensitivity reactions was measured and the capacity of the skin to accomodate a large increase in flow during the inflammatory response was established.