IN-SITU HYBRIDIZATION OF ATRIAL-NATRIURETIC-PEPTIDE MESSENGER-RNA IN THE ENDOTHELIAL-CELLS OF HUMAN UMBILICAL VESSELS

The localization of mRNA encoding preproatrial natriuretic peptide (AN P) was investigated in cultured human umbilical vein endothelial cells (HUVEC) and tissue preparations of umbilical vein and artery. The tec hniques used were in situ hybridization and in situ hybridization comb ined with immunocytochemistry, using P-32-radiolabelled and non-radioa ctive digoxigenin labelled complementary RNA probes. Human ANP mRNAs a re mainly localized in the endothelial cells of the umbilical vein and , to a lesser extent, in the endothelial cells of the umbilical artery . The autoradiographic labelling and the intensity of digoxigenin stai ning were significantly reduced by treatment with RNase before in situ hybridization. This study provides unequivocal evidence for the expre ssion of the ANP gene in the endothelial cells of human umbilical vess els, confirming that these endothelial cells have the ability to synth esize this peptide. The functional significance of the presence of the ANP mRNA in the endothelial cells of human umbilical vessels is discu ssed.