Development of enhanced blood flow responses to prostaglandin E1 in carrageenan-induced granulation tissue

The distribution of cardiac output (c.o.) was measured by the radioactive microsphere method in rats at different time intervals after the implantation of carrageenanimpregnated sponges. The amount of blood distributed to the developing granulomata increased from day 5 after sponge implantation to day 7, but showed no further increase at day 10. A similar pattern in blood flow was observed in the skin covering the granulomata. Injection of PGE₁ (100 ng) into the sponges led to an increase in blood flow, the magnitude of which became gradually larger between days 5 and 10. A similar, though less marked increase in sensitivity to PGE₁ was observed in the skin covering the granulomata, PGE₁ causing a significant increase in blood flow to the skin on day 10. These changes in sensitivity to exogenous PGE₁ may be due to decreasing levels of endogenous PGE and/or maturation of the newly formed blood vessels in the granulation tissue.