Jordan University of Science and Technology

Contraction and relaxation signaling in gastrointestinal smooth muscle


Authors:  Al-Shboul, O

Abstract:  
The gastrointestinal (GI) tract is a complex multi-organ system with tissues that differ structurally and functionally. The dynamic interactions between the neuronal, muscular, immune, and glandular tissues allow the GI tract to perform its main physiological functions, which include digestion, absorption, excretion, and protection. Normal gut motility provides for the mixing and propulsion of intraluminal contents to enable efficient digestion of food, progressive absorption of nutrients, and evacuation of residues. These fine and delicate GI tract movements are generated by a highly-regulated interaction between an intricate network of neurons located within the wall of the alimentary canal (ie the enteric nervous system), an intrinsic pacemaker system (ie interstitial cells of Cajal or ICC) and the final effector cells (ie smooth muscle cells). GI tract smooth muscle possesses distinct regional and functional properties that distinguish it from other types of visceral and vascular smooth muscle. Gut smooth muscles contract spontaneously in the absence of neural, humoral, or hormonal stimuli and in response to stretch. They contract as a syncytium (ie contract in unison) and therefore classified as unitary type smooth muscle. The molecular mechanisms underlying GI smooth muscle contraction and relaxation signaling pathways are the subject of this review.