sentences:  While 86 alkaloids have been discovered throughout "Rauvolfia vomitoria", ajmaline is mainly isolated from the stem bark and roots of the plant.Due to the low bioavailability of ajmaline, a semisynthetic propyl derivative called prajmaline (trade name Neo-gilurythmal) was developed that induces similar effects to its predecessor but has better bioavailability and absorption.Ajmaline was first discovered to lengthen the refractory period of the heart by blocking sodium ion channels, but it has also been noted that it is also able to interfere with the hERG (human Ether-a-go-go-Related Gene) potassium ion channel.