Xuan-zheng, Shi
Xuan-Zheng (Peter) Shi, PhD
Associate Professor

Division: Gastroenterology
Department: Internal Medicine


Dr. Shi is currently an Associate Professor of Internal Medicine in the Division of Gastroenterology and Hepatology in the Department of Internal Medicine at the University of Texas Medical Branch (UTMB) in Galveston, Texas.

Dr. Shi earned his M.D. from Wannan Medical College in China, and received his graduate education and post-doctoral training at the Medical College of Wisconsin. His research has been focused on the gastrointestinal smooth muscle and nervous control of digestive function since 1987, when he was a faculty member of medical physiology at Lanzhou University College of Medicine. Dr. Shi won the only fellowship award of the International Union of Physiological Sciences for '92-'93. He has authored and co-authored 25 peer-reviewed journal articles and book chapters, and served as reviewer for multiple peer-reviewed journals. Dr. Shi joined the Division as an Assistant Professor in 2002, and was promoted to Associate Professor in 2008.

Research Interests

Several gastrointestinal conditions such as achalasia, gastric stasis, pseudo-obstruction, and mechanical obstruction demonstrate a distended lumen, and obstructive symptoms. These conditions can be classified as obstructive bowel disorders (OBDs). The motility function is impaired in OBDs, and the motility dysfunction is responsible for symptoms such as distension, bloating, vomiting, abdominal pain, and constipation encountered in these disorders. The mechanisms for the impaired motility function in OBDs are not known. Dr. Shi and his colleagues have found that mechanical stretch in OBDs induces marked expression of mechanically sensitive genes such as COX-2 in the gastrointestinal tract. These stretch-induced genes play a critical role in pathophysiology of bowel obstruction, pseudo-obstruction, achalasia, and constipation. Dr. Shi's lab has been awarded by NIH funding to investigate the mechanism of mechanical stretch-induced gene expression in the gut. They have found that blockers of this pathway have therapeutic benefits in the managements of motility dysfunction in OBDs. A further understanding of the signaling mechanism involved in stretch-induced gene expression in the gut will direct novel treatments towards these disorders. 

Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) are great digestive health challenges. Motility dysfunction and visceral hypersensitivity are responsible for symptoms such as diarrhea, constipation, abdominal pain and discomfort in these conditions. Dr. Shi has been collaborating with Dr. Sarna to characterize the molecular mechanisms of gastrointestinal motility changes and hypersensitivity in IBD and IBS. One of the most striking findings of Dr. Shi's research is that gut smooth muscle is not just a "passive" contractile tissue; it also "actively" participates in the processes of inflammation and visceral sensitization by secreting cytokines, chemokines, and other inflammatory mediators.

  1. Shi, XZ, Lin YM, Powell DW, Sarna SK. Pathophysiology of motility dysfunction in bowel obstruction: Role of stretch-induced COX-2. Am. J. Physiol Gastrointest Liver Physiol. 2011 Jan; 300(1):G99-G108. Epub 2010 Nov 4.
  2. Shi, XZ, Winston JH, Sarna SK. Differential immune and genetic response in rat models of Crohn's colitis and ulcerative colitis. Am. J. Physiol Gastrointest Liver Physiol. 2011 Jan; 300(1):G41-G51. Epub 2010 Oct 14.
  3. Shi, XZ, and SK Sarna: Homeostatic and therapeutic roles of VIP in smooth muscle function: Myo-immune interactions. Am. J. Physiol Gastrointest Liver Physiol. 2009 Oct; 297(4):G716-25. Epub 2009 Aug. 6th.
  4. Choudhury BK, Shi XZ, Sarna SK. Norepinephrine mediates the transcriptional effects of heterotypic chronic stress on colonic motor function. Am. J. Physiol Gastrointest Liver Physiol. 2009 Jun; 296(6): G1238-47. Epub 2009 Apr 9.
  5. Choudhury BK, Shi XZ, Sarna SK: Gene plasticity in colonic circular smooth muscle cells underlies motility dysfunction in a model of post-infective IBS. Am. J. Physiol Gastrointest Liver Physiol. 2009 Mar; 296(3): G632-42.  
  6. Shi, XZ, and SK Sarna: Gene therapy of Cav1.2 channel with VIP, VIP receptor agonists and VIP receptor antagonists: A novel approach to designing pro-motility and anti-motility agents. Am. J. Physiol Gastrointest Liver Physiol. 2008 Jul; 295(1):G187-G196.
  7. Shi, XZ, BK Choudhury, PJ Pasricha, and SK Sarna. A Novel Role of VIP in Colonic Motility Function: Induction of Excitation-Transcription Coupling in Smooth Muscle Cells. Gastroenterology. 132(4):1388-400; 2007.
  8. Sarna, SK and XZ Shi: Function and Regulation of Colonic Contractions in Health and Disease. In: Johnson LR, Barrett KE, Gisham FK, Merchant JL, Said HM, Ward JD, eds. Physiology of the Gastrointestinal Tract 4th ed, pp. 965 to 993, Chapter 39. San Diego, CA: Elsevier, 2006.
  9. Shi, XZ, Konrad Pazdrak, Nehad Saada, Bosong Dai, Philip Palade and Sushil K. Sarna. Negative transcriptional regulation of human colonic smooth muscle Cav1.2 channels by p50 and p65 subunits of nuclear factor-κB. Gastroenterology. 129: 1518- 1532, 2005.
  10. Shi, XZ and SK Sarna. Transcriptional regulation of inflammatory mediators secreted by human colonic circular smooth muscle cells. Am J Physiol (Gastrointest Liver Physiol.) 289(2):G274-84, 2005.
  11. Pazdrak, K, XZ Shi and SK Sarna. TNF-α suppresses human colonic smooth muscle contractility by SP1 and NF-κB mediated induction of ICAM-1. Gastroenterology 127 (4): 1096-1109, 2004.
  12. Shi, XZ and SK Sarna. G-protein-mediated dysfunction of excitation-contraction coupling in ileal inflammation. Am. J. Physiol Gastrointest Liver Physiol. 286 (6): G899–G905, 2004.
  13. Shi, XZ, PF Lindholm, SK Sarna: Oxidative Stress and Inflammation –Induced Activation of NF-κB in Canine Colonic Circular Smooth Muscle Cells. Gastroenterology 124 (5): 1369 –1380, 2003.
  14. Shi, XZ and SK Sarna. Impairment of Ca2+ mobilization in circular muscle cells of the inflamed colon. Am. J. Physiol. (Gastrointest. Liver Physiol 41): G234 –G242, 2000.
  15. Shi, XZ and SK Sarna. Differential inflammatory modulation of canine ileal longitudinal and circular muscle cells. Am. J. Physiol. (Gastrointest. Liver Physiol. 40): G341 –G350, 1999.