[Mucosal microcirculation and angiogenesis in gastrointestinal tract]

In this review, various aspects of gastrointestinal microcirculation were described. Endothelin-1, vasoconstrictor, is elevated in gastric mucosa, causes gastric ischemia and results in gastric ulceration in human and animals under physical stress. Vasodilators such as NO anticipate the alove actions of endothelin, and thereby protect mucosa from injury. Once ulcer is developed, angiogenesis plays a key role in its healing. Various growth factors, cyclooxygenases-1 and -2, and non-peptide angiogenic factors stimulate this phenomenon and participate in ulcer healing. However, acidic conditions, H. pylori and its product, ammonia, suppress angiogenesis in vitro and in vivo. These evidences may explain why ulcer heals so slowly in gastroduodenal mucosa.