Nicotine-induced adrenal beta-arrestin1 upregulation mediates tobacco-related hyperaldosteronism leading to cardiac dysfunction

Figure 4 Effect of adrenal βarrestin1 knockdown on nicotine-dependent hyperaldosteronism and cardiac dysfunction in vivo. A: Circulating aldosterone levels in rats injected i.p. with 1 mg/kg per day nicotine or saline (control) for 7 consecutive d. ^aP < 0.05; n = 5 rats/group; B: Ejection fraction [EF (%)] of these animals at the end of the saline or nicotine treatments. ^aP < 0.05; n = 5 rats/group; C: Immunoblotting for βarrestin1 in adrenal protein extracts isolated from rats at 7 d post-injection with βarrestin1-specific siRNA or scrambled (Scr) siRNA directly into their adrenal glands. A representative blot of three independent rat adrenal protein extracts is shown, along with glyceraldehyde 3-phosphate dehydrogenase as loading control, confirming an > 90% βarrestin1 protein knockdown in the adrenal glands in vivo; D: Circulating aldosterone levels of rats having adrenal βarrestin1 knocked-down (rrestin1-specific siRNA) or not (scrambled siRNA-injected, Scr) and treated with 1 mg/ kg per day i.p. nicotine or saline (control) for 7 consecutive d, at the end of these treatments. E: EF (%) of rats having adrenal βarrestin1 knocked-down (rrestin1-specific siRNA) or not (scrambled siRNA-injected, Scr) and treated with 1 mg/kg per day i.p. nicotine or saline (control) for 7 consecutive d, at the end of these treatments. ^aP < 0.05 vs Saline; ^bP < 0.05 vs Scr; n = 5 rats/group. Scr: Scrambled; GAPDH: Glyceraldehyde 3-phosphate dehydrogenase; Arrb1: Arrestin1-sepcific; EF (%): Ejection fraction.