Carsatrin is purinylpiperazine derivative patented by Ortho Pharmaceutical Corp. as cardiotonic and antiarrhythmic. Carsatrin acts as positive inotropic agent that increases twitch tension and prolongs the action potential (AP) duration of ventricular muscle without affecting the Na+,K+-ATPase, adenylyl cyclase, phosphodiesterase isozymes, or cardiac myofilaments. Carsatrin’s positive inotropic effect can be prevented by tetrodotoxin but not by the adrenergic antagonists timolol, yohimbine, or prazosin