Factors affecting the termination of cardiovascular actions of 10,10-difluoro,13-dehydroprostacyclin.

Experiments were conducted to determine why 10,10-difluoro,13-dehydroprostacyclin (DF2-PGI2) has a long vascular relaxant activity in vitro but like PGI2 has a short duration of effect in vivo. DF2-PGI2 produced depressor responses in anesthetized dogs which were not affected by nephrectomy suggesting that the kidney was not responsible for the termination of action. DF2-PGI2 given intravenously or into the ascending aorta produced depressor responses of a similar magnitude but injection of the same doses into the hepatic portal circulation resulted in a large attenuation of responses. The data suggest hepatic, but not pulmonary, metabolism of DF2-PGI2. Injection or infusion of PGI2 and DF2-PGI2 into the hindlimb circulation caused vasodilatation of a similar duration suggesting diffusion from tissue sites as another mechanism of termination of action.