L-arginine improves transmission of perfusion pressure to the renal interstitium in Dahl salt-sensitive rats

Abstract

L-Arginine normalizes pressure natriuresis in Dahl salt-sensitive (DS) rats. To determine the role of renal interstitial hydrostatic pressure (RIHP) in this phenomenon, we measured RIHP determined by servo-null during acute changes in renal perfusion pressure in anesthetized DS rats receiving L-arginine (300 mg.kg-1.day-1 ip) or vehicle for 3 wk. Dahl salt-resistant (DR) rats were controls. As observed previously, the slope of the pressure-natriuresis relationship was greater (P < 0.05) in L-arginine-treated DS rats than vehicle DS rats and not different from DR rats. The slope of the relationship between renal perfusion pressure and RIHP was greater (P < 0.05) in DR rats than vehicle DS rats. In L-arginine-treated DS rats the slope of this relationship was greater (P < 0.05) than that in vehicle DS rats and not different from DR rats. Removal of the renal capsule blunted the pressure-natriuresis relationship in L-arginine-treated DS rats but had no effect in vehicle DS rats. Thus L-arginine improves transmission of perfusion pressure into the renal interstitium in DS rats and may contribute to the improved pressure-natriuresis response.