Quazinone（Ro 13-6438）是一种选择性磷酸二酯酶（PDE）抑制剂，是一种具有血管舒张特性的新型强心药。据报道抑制心肌PDE活性并提高细胞内环AMP（cAMP）水平，在离体的豚鼠乳头肌中引起正性肌力反应。已显示在部分去极化的乳头肌中以浓度依赖的方式增加上冲程速度，过冲和慢动作电位的持续时间。 Quazinone (Ro 13-6438) is a selective phosphodiesterase (PDE) inhibitor, and a novel cardiotonic agent with vasodilating properties. It has been reported to inhibit myocardial PDE activity and elevate levels of intracellular cyclic AMP (cAMP), causing a positive inotropic response in isolated guina pig papillary muscle. It has been shown to increase the upstroke velocity, overshoot, and duration of slow action potentials in a concentration-dependent fashion in partially depolarized papillary muscles.