TAC1 and inflammatory bowel disease: In earlier studies (Norton et al., 2021a), we found that despite impaired sensory vasodilation with IBD, there was not a significant decrease in the content or release of the sensory neurotransmitters CGRP and substance P. Similarly, the function of CGRP receptors, the primary vasodilatory peptide, released was unaltered with IBD, as shown by exogenous CGRP concentration-response curves.