Figure 4.

Nuclear AT1Rs and AT2Rs regulate RNA synthesis in isolated atrial fibroblast nuclei; IP3R and NO are underlying mediators. A, Transcription initiation was measured as [α³²P]UTP incorporation in nuclei treated with increasing concentrations of angiotensin‐II (Ang‐II). **P<0.01, ***P<0.001, by 1‐way ANOVA with Bonferroni‐adjusted t test vs control (CTL). B, [α³²P]UTP incorporation was measured in nuclei treated with Ang‐II (100 nmol/L) alone, or pretreated with α‐amanitin (5 μg/mL), valsartan (1 μmol/L), or PD123177 (1 μmol/L) and then stimulated with Ang‐II. ***P<0.001, by 1‐way ANOVA with Bonferroni‐adjusted t test vs Ang‐II. C, NO production was determined by DAF‐2 fluorescence in nuclei stimulated with Ang‐II (100 nmol/L) alone, or pretreated with valsartan (1 μmol/L), PD123177 (1 μmol/L), or l‐NAME (1 mmol/L) and then stimulated with Ang‐II. Data represent mean±SEM of at least 4 separate experiments performed in triplicate and normalized to control. ***P<0.001 vs control. D, Immunoblotting for eNOS in cytosolic and nuclear enriched fractions. The positions of molecular weight markers are indicated at the left (in kDa). E, [α³²P]UTP incorporation measured in fibroblast nuclei treated with L‐162313 (AT1R‐selective agonist, 1 μmol/L) or CGP 42112A (AT2R‐selective agonist, 1 μmol/L), alone or in combination with either l‐NAME (1 mmol/L) or 2‐APB (100 μmol/L). *P<0.05 by 1‐way ANOVA with Bonferroni‐adjusted t test for comparisons shown. All results are mean±SEM. AT1Rs indicates Ang‐II type 1 receptors; 2‐APB, 2‐aminoethoxydiphenyl borate; DAF‐2, 4,5‐diaminofluorescein; eNOS, endothelial nitric oxide synthase; l‐NAME, N(G)‐nitro‐l‐arginine methyl ester.