Interaction of FCE 22176, a stable prostacyclin analogue, with different prostaglandins in guinea-pig trachea and atria.

FCE 22176, a stable derivative of a PGI2 analogue, was studied in guinea-pig isolated atria and trachea. The compound was without inotropic or chronotropic effects in spontaneously beating atria and did not alter tracheal tone. By contrast, FCE 22176 competitively antagonized the inotropic effect of PGI2 on atria, and inhibited the PGI2-induced contraction of tracheal chains. Furthermore, in tracheal chains, FCE 22176 was able to antagonize the contractile effect of PGF2 alpha, and to enhance PGE2-induced relaxation. These data support our previous findings that FCE 22176 is a PGI2 antagonist, and provide evidence also for a more complex effect on prostaglandin receptors.