Potentiating effect of 3-isobutyryl-2-isopropylpyrazolo-[1,5a]-pyridine (KC-404), a new cerebral vasodilator with anti-platelet activity, on prostacyclin-induced increase of cyclic AMP content in platelets of rat.

1. The effect of KC-404, a new antiplatelet and cerebrovasodilating drug, on prostacyclin (PGI2)-induced accumulation of cyclic AMP was investigated using washed platelets of rat. 2. PGI2 enhanced the cyclic AMP content in a concentration-dependent manner. 3. KC-404 at a relatively high concentrations (above 4.34 microM) significantly increased the maximum cyclic AMP accumulation induced by PGI2, without change in its sensitivity. 4. It is concluded that KC-404 potentiates a mechanism of action of PGI2, and a possible relevance of KC-404 for the treatment of cerebrovascular disorders with a tendency of accompanying thromboembolism is suggested.