Sodium-induced rise in blood pressure is suppressed by androgen receptor blockade

Our objective was to test the hypothesis that 1) a high Na (HNa, 3%) diet w ould increase blood pressure (BP) in male Wistar-Kyoto (WKY) and spontaneou sly hypertensive Y chromosome (SHR/y) rat strains in a territorial colony; 2) sympathetic nervous system (SNS) blockade using clonidine would lower BP on a HNa diet; and 3) prepubertal androgen receptor blockade with flutamid e would lower BP on a HNa diet. A 2 x 4 factorial design used rat strains ( WKY, SHR/y) and treatment [0.3% normal Na (NNa), 3% HNa, HNa/clonidine, and HNa/flutamide]. BP increased in both strains on the HNa diet (P< 0.0001). There was no significant decrease in BP in either strain with clonidine tre atment. Androgen receptor blockade with flutamide significantly decreased B P in both strains (P< 0.0001) and normalized BP in the SHR/y colony. Neithe r heart rate nor activity could explain these BP differences. In conclusion , a Na sensitivity was observed in both strains, which was reduced to normo tensive values by androgen blockade but not by SNS blockade.