Regulation of brain renin-angiotensin system by benzamil-blockable sodium channels.

Changes in the renin-angiotensin system (RAS) mRNAs in the brain and the kidney of rats after administration of DOCA and/or sodium chloride were assessed by use of a competitive PCR method. Benzamil, a blocker of amiloride-sensitive sodium channels, was infused intracerebroventricularly or intravenously for 7 days in DOCA-salt or renal hypertensive rats, and the effects of benzamil on the brain RAS mRNAs were determined. Renin and ANG I-converting enzyme (ACE) mRNAs were not downregulated in the brain of rats administered DOCA and/or salt; however, these mRNAs were decreased in the kidney. Intracerebroventricular infusion of benzamil decreased renin, ACE, and ANG II type 1 receptor mRNAs in the brain of DOCA-salt hypertensive rats but not in the brain of renal hypertensive rats. The gene expression of the brain RAS, particularly renin and ACE, is regulated differently between the brain and the kidney in DOCA-salt hypertensive rats, and benzamil-blockable brain sodium channels may participate in the regulation of the brain RAS mRNAs.