Ts. Larson et Jc. Lockhart, RESTORATION OF VASA-RECTA HEMODYNAMICS AND PRESSURE NATRIURESIS IN SHR BY L-ARGININE, American journal of physiology. Renal, fluid and electrolyte physiology, 37(5), 1995, pp. 907-912
An increase in medullary blood flow has been implicated as a mediator
of the natriuresis following increases in renal perfusion pressure (RP
P). We examined whether administration of L-arginine, the substrate fo
r nitric oxide production, restores the impaired vasa recta hemodynami
c response to increases in RPP and the blunted pressure natriuresis of
the spontaneously hypertensive rat (SHR). The response of descending
(Q(DVR)) and ascending vasa recta blood flow (Q(AVR)) and of urinary s
odium excretion (UNaV) was examined as RPP was increased by means of a
n adjustable aortic clamp placed above the renal arteries in young SHR
and Wistar-Kyoto (WKY) rats. When RPP was increased in SHR receiving
infusion of L-arginine (n = 7), Q(DVR) and Q(AVR) increased significan
tly in association with increases in UN,V. In SHR receiving the inacti
ve enantiomer, D-arginine (n = 7), similar increases in RPP failed to
increase Q(AVR) and Q(DVR) and were associated with an attenuated incr
ease in UNaV. WKY animals infused with either D-arginine or L-arginine
had increases in Q(DVR), Q(AVR), and UNaV in response to increases in
RPP that were of similar magnitude to SHR receiving L-arginine. Thus
the administration of L-arginine to SHR restores the pressure-dependen
t increases in renal medullary hemodynamics in association with restor
ation of pressure natriuresis.