Localization of angiotensin-converting enzyme (ACE) mRNA in rabbit gastric mucosa by in situ hybridization.

In a previous study we showed, by immunohistochemical analysis on rabbit fundic mucosa, that in addition to its usual presence on the luminal plasma membrane of endothelial cells, angiotensin converting-enzyme (ACE) was localized inside granules of surface and neck mucous cells and within granules of chief cells. The aim of the present study was to localize ACE mRNA in cells of the rabbit fundic mucosa by in situ hybridization with a 35S-labeled probe. This probe was a cDNA fragment (406 BP) encoding a portion of the rabbit ACE mRNA obtained by reverse transcription followed by polymerase chain reaction on total RNA extracted from fundic mucosa. ACE mRNAs were detected in mucous and chief cells and in endothelial cells of the mucosal vasculature. These results are in complete agreement with our prior studies which showed by immunohistochemical analysis that ACE is present in these cells. Our findings therefore suggest that ACE previously detected in epithelial cells of the rabbit gastric mucosa is actually synthesized within these cells.