Nm. Atucha et al., EFFECTS OF NITRIC-OXIDE INHIBITION ON THE RENAL PAPILLARY BLOOD-FLOW RESPONSE TO SALINE-INDUCED VOLUME EXPANSION IN THE RAT, Clinical science, 86(4), 1994, pp. 405-409
1. Evidence indicates that nitric oxide (NO) exerts a paracrine influe
nce in the renal medulla. Increases in papillary blood flow are though
t to be an important determinant of the renal response to extracellula
r volume expansion. Therefore, in the present study, we have evaluated
the role of NO in mediating papillary blood flow (laser-Doppler flowm
etry) and excretory responses to volume expansion with isotonic saline
(3% body weight, 15 min). 2. Infusion of the NO synthesis inhibitor N
-omega-nitro-L-arginine methyl ester (10 mu g min(-1) kg(-1)), signifi
cantly attentuated the renal diuretic and natriuretic responses to vol
ume expansion as well as the renal hydrostatic interstitial pressure i
ncrease induced by this manoeuvre. The percentages of the water and so
dium excreted in Ih by the N-omega-nitro-L-arginine methyl ester-pretr
eated animals were 36% and 40% of the load, whereas those of the contr
ol animals were 44% and 65%, respectively. 3. In similar experiments p
erformed in the exposed papilla of Munich Wistar rats, the same dose o
f N-omega-nitro-L-arginine methyl ester reduced basal papillary blood
flow and blunted the elevation in papillary blood flow induced by volu
me expansion (6% versus 16% in the control animals). 4. These results
indicate that the inhibition of NO synthesis blunts the renal excretor
y and papillary responses to volume expansion, suggesting that NO modu
lates these responses through changes in papillary blood flow and rena
l interstitial hydrostatic pressure.