We examined whether central nitric oxide is involved in blood pressure (BP) regulation in deoxycorticosterone acetate (DOCA)-salt hypertension. DOCA-salt rats were intracerebroventricularly infused (ICV) NG-monomethyl L-arginine (L-NMMA) for 4 weeks at either low (0.08 mg/kg/d; n=8) or high (0.16 mg/kg/d; n=8) dose. Saline ICV (n=9) and intraperitoneal infused L-NMMA (low, n=6; high dose, n=6) were served as controls. Also, L-NMMA ICV (low, n=6; high dose, n=6) was conducted in normal rats. At week 3 and after, DOCA-salt with low L-NMMA ICV showed a higher BP than saline ICV (at week 4: 167.4±3.6 vs. 150.3±3.9 mm Hg, P<0.01); this difference of BP was cancelled after ganglionic block. High L-NMMA ICV did not affect the trend of BP; however, it caused a reduced amount of saline drinking and a less estimated sodium retention than saline or low L-NMMA ICV (for 3 wk; 47.5±1.1 vs. 66.0±3.7 and 61.7±2.5 mmol, P<0.01). In normal rats, high, but not low, L-NMMA ICV elevated BP with no effect on drinking behavior. Intraperitoneal infused L-NMMA did not affect the development of hypertension and/or sodium balance. These data suggested that, in DOCA-salt, central nitric oxide is involved in BP regulation through the dual action on sympathetic nervous activity and sodium balance.
Department of Cardiovascular Medicine, Course of Medical and Dental Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki 852-8501, Japan
Reprints: Shinji Seto, MD, PhD, Department of Cardiovascular Medicine, Course of Medical and Dental Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki 852-8501, Japan (e-mail: firstname.lastname@example.org).
Received for publication December 7, 2005; accepted April 11, 2004