Abstract
Traxanox sodium salt pentahydrate (9-chloro-5-oxo-7-(1H-tetrazol-5-yl)-5H-[1] benzopyrano [2, 3-b] pyridine sodium salt pentahydrate, Code No. Y-12, 141) (traxanox sodium) inhibited cyclic AMP phosphodiesterase in the lungs and hearts of rats. The inhibitory effect of traxanox sodium was more potent than that of both theophylline and sodium cromoglycate, but was less potent than that of papaverine. In the low Km (2 μM) enzyme of lungs the inhibition by traxanox sodium was competitive and its inhibition constant (Ki) was 66.7 μM. Intraperitoneal injection of traxanox sodium (100 mg/kg) synergistically enhanced the isoproterenol-induced increase of cyclic AMP in the plasma of rats.
