To investigate whether angiotensin II type 2 (AT2) receptor (AT2-r) promoter activity and expression are modulated by angiotensin II (Ang II), and whether the AT1 receptor (AT1-r) is involved in this effect. DESIGN AND METHODS: Primary endothelial cells obtained from NEONATAL rat aorta, expressing both receptors, were transfected with the rat AT2-r promoter region cloned into a pCAT-reporter vector. The reporter-expression study was performed in a transient transfection assay system. Transfected cells were studied following angiotensin-converting enzyme inhibition to prevent endogenous formation of Ang II. Cells were subsequently stimulated for 6 h with Ang II, either alone or in combination with the AT1-r antagonist DuP753. AT2-r mRNA was assessed by RNase protection assay during the same pharmacological stimuli. RESULTS: Stimulation with Ang II caused an increase in promoter activity (+50%, P