TRPA1 and General Anesthetics

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DESCRIPTION (provided by applicant): General anesthetics (GAs) are a diverse group of chemicals with the shared ability to induce reversible unconsciousness. Although these drugs have revolutionized surgery they are still less than ideal. In particular, many of these drugs provoke pain/irritation upon administration. Inhalant GAs can provoke airway irritation and sympathetic activation. Moreover, there is emerging evidence that noxious anesthetics have the potential to exacerbate post-surgical pain and inflammation. Approximately 200 million surgeries are performed worldwide each year, and therefore, understanding how GAs interacts with TRP channels is highly desirable. Our previous data show that desflurane/isoflurane excites sensory nerves by selectively activating the "mustard-oil" receptor (TRPA1). A major goal of this proposal is to elucidate amino acids in TRPA1 that are critical for anesthetic agonism. We hypothesize that desflurane binds to a cavity between the 5th and 6th transmembrane domains of TRPA1. We will explore 2 specific aims. (1) Using a genetic approach we will determine the putative sites on TRPA1 necessary for activation by desflurane. Our preliminary data reveal a critical role for transmembrane 5 of TRPA1 in anesthetic sensing, and thus we will focus on amino acids in this region. Further, we will model docking of desflurane to TRPA1 to validate our genetic/functional data and verify that desflurane directly interacts with TRPA1. (2) We will test the ability of desflurane analogs (including enantiomers) to activate TRPA1. These analogs are designed to probe the steric and electronic properties of the methoxy group in desflurane predicted to specifically interact with TRPA1.