Expression of adrenomedullin in portal hypertensive gastric mucosa of rats

We examined the expression and localization of adrenomedullin (AM) mRNA, AM receptor (AM-R) mRNA and AM protein in normal and portal hypertensive (PHT) rat gastric mucosa. Methods included competitive reverse transcription polymerase chain reaction (RT/PCR), in situ hybridization and Western blot analysis. Both AM mRNA and AM-R mRNA were strongly expressed not only in normal rat gastric mucosa but also PHT rat gastric mucosa. While total AM and AM-R mRNA abundance was similar in both normal and PHT stomachs, in the superficial mucosa - where major defense mechanisms are located - their expression was significantly reduced in PHT rats by 33% (AM mRNA) and 25% (AM-R mRNA) (both p < 0.05). AM protein was also expressed similarly in both normal and PHT gastric mucosa. We conclude that AM and its receptor play a role in regulation of gastric mucosal microcirculation and thus gastric mucosal defense.