L-ARGININE IMPROVES TRANSMISSION OF PERFUSION-PRESSURE TO THE RENAL INTERSTITIUM IN DAHL SALT-SENSITIVE RATS

L-Arginine normalizes pressure natriuresis in Dahl salt-sensitive (DS) rats. To determine the role of renal interstitial hydrostatic pressur e (RIHP) in this phenomenon, we measured RIHP determined by servo-null during acute changes in renal perfusion pressure in anesthetized DS r ats receiving L-arginine (300 mg.kg(-1).day(-1) ip) or vehicle for 3 w k. 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 diffe rent from DR rats. The slope of the relationship between renal perfusi on 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 wa s greater (P < 0.05) than that in vehicle DS rats and not different fr om DR rats. Removal of the renal capsule blunted the pressure-natriure sis relationship in L-arginine-treated DS rats but had no effect in ve hicle DS rats. Thus L-arginine improves transmission of perfusion pres sure into the renal interstitium in DS rats and may contribute to the improved pressure-natriuresis response.