Chemical. CAS 57444-62-9. Formula C37H40O9. MW 628.72. Isolated from Euphorbia resinifera. Highly potent TRPV1 agonist. Resiniferatoxin RTX is a phorbol-related diterpene ester analog of capsaicin. RTX is a highly potent transient receptor potential vanilloid 1 TRPV1 agonist Ki=43pM and acts as a selective modulator of primary afferent neurons. TRPV1 or vanilloid receptor 1 is a non-selective cation channel that is involved in the detection and transduction of nociceptive stimuli. TRPV1 is expressed in the plasma membrane of sensory neurons and stimulation by RTX causes this ion channel to become permeable to cations, especially calcium. The influx of cations causes the neuron to depolarize, transmitting signals similar to those that would be transmitted if the innervated tissue were being burned or damaged. This stimulation is followed by desensitization and analgesia, in part because the nerve endings die from calcium overload.