Expression of endothelin receptors in the gastric mucosa of portal hypertensive rats

Abstract

Portal hypertensive gastropathy is an abnormal circulatory state in gastric mucosa with vascular dilatation due to portal hypertension. The aim of the present study was to evaluate expression of endothelin receptors and their roles in the portal hypertensive gastric mucosa. Portal hypertensive rats were generated by staged portal vein occlusion. Expression of endothelin-A receptor and endothelin-B receptor mRNA was examined by reverse transcriptase-polymerase chain reaction, and protein were examined by immunohistochemistry. The changes of mucosal microcirculation by endothelin receptor antagonists were measured with in vivo microscope. Expression of endothelin-A receptor mRNA was increased significantly in portal hypertensive rats in comparison with sham-operated control rats (P < 0.05). There was no significant difference between the two groups in endothelin-B receptor mRNA expression. Vessels of the gastric mucosa were dilated, and intravessel blood flow was increased significantly in the portal hypertensive group (P < 0.05). Diameters of mucosal vessels and blood flow were increased significantly by endothelin-A receptor antagonist (BQ-485) in the portal hypertensive rats. Endothelin-B receptor antagonist (IRL-1038) had no significant effect on mucosal microcirculation. These data suggest that increased expression of endothelin-A receptor in the portal hypertensive gastric mucosa may be related to the regulation of gastric microcirculation.