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Handbook of Electrogastrography$
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Kenneth L. Koch and Robert M. Stern

Print publication date: 2003

Print ISBN-13: 9780195147889

Published to Oxford Scholarship Online: November 2020

DOI: 10.1093/oso/9780195147889.001.0001

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PRINTED FROM OXFORD SCHOLARSHIP ONLINE (oxford.universitypressscholarship.com). (c) Copyright Oxford University Press, 2021. All Rights Reserved. An individual user may print out a PDF of a single chapter of a monograph in OSO for personal use. date: 17 June 2021

Properties of Electrical Rhythmicity in the Stomach

Properties of Electrical Rhythmicity in the Stomach

Chapter:
(p.13) 2 Properties of Electrical Rhythmicity in the Stomach
Source:
Handbook of Electrogastrography
Author(s):

Kenton M. Sanders

Tamas Ördög

Publisher:
Oxford University Press
DOI:10.1093/oso/9780195147889.003.0006

Gastric peristaltic contractions are the basis for emptying of solids from the stomach. These events begin in the mid to high corpus region, develop into a ring around the stomach, and spread down the length of the stomach to the pylorus. The pressure wave resulting from gastric peristalsis pushes the contents of the stomach toward the pyloric sphincter, but a nearly simultaneous contraction of the ring of muscle in the pyloric canal and the terminal antrum ultimately forces much of the food in the retrograde direction, toward the body of the stomach. Sheer forces that develop as a result of this forceful retropulsion cause mechanical disruption of solid particles. Repetitive peristaltic contractions (e.g., in the human these events occur about 3 times per minute), over a period of time, reduces ingested foods to small particles. The action of gastric peristalsis in the distal stomach facilitates emptying and the reduced particle diameter aides in chemical digestion of foods in the small intestine. Pathophysiological conditions that disrupt or disorganize gastric peristalsis can impair or delay normal gastric emptying. Gastric peristaltic contractions result from depolarization of the plasma membranes of smooth muscle cells. For many years it has been known that gastric muscles display periodic (or rhythmic) electrical activity in which membrane potential oscillates between negative potentials and more depolarized levels. The oscillations in membrane potential are known as electrical slow waves (see Color Figs. 2.1 and 2.2 in separate color insert). Slow waves are generated within the tunica muscularis of the proximal corpus along the greater curvature of the stomach, and these events spread around the circumference and down the stomach to the pylorus. A greater velocity of propagation around the stomach than down the stomach causes development of a ring of excitation, and this is the electrical basis underlying gastric peristaltic contractions. Studies have shown that electrical slow waves are generated by specialized pacemaker cells, known as interstitial cells of Cajal (ICCs). The main pacemaker ICCs in the stomach form a dense network of electrically coupled cells between the circular and longitudinal muscle layers of the corpus and antrum.

Keywords:   Diabetic gastroparesis, Forskolin (FSK), Inositol triphosphate (IP3), Interstitial cells of Cajal (ICCs), Mechanical threshold, Peristalsis, gastric, Resting membrane potential, Spike potentials, Uncoupling

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