Spasm of gastric muscularis mucosae might play a key role in causing focal mucosal ischemia and ulceration. An experimental study in guinea pigs.

While transilluminating guinea pig gastric wall, we noticed foci of irregular compression of submucosal veins and arteries, featuring parallel bands across arteries, with complete cessation of blood flow, mucosal pallor, and shrinkage of the area. Other features demonstrated that this was not due to artifactual pressure. We attribute it to compression of vessels by spasm of the muscularis mucosae, because these vessels are embedded in the muscle. Arteries and veins returned to normal with normal mucosal perfusion, either spontaneously within 5 min, or within 5 sec following mucosal stimulation. However, in 20%, "ischemia" remained for 2-3 hr, resulting in full-thickness necrosis of the underlying mucosa but not in surrounding areas. Since in man mucosal arteries pass through the muscularis mucosae before reaching mucosa, and in view of evidence that they may be end arteries, we suggest that stress-induced spasm of muscularis mucosae may play an important role in human acute and chronic ulceration.