Dietary sodium affects the systemic and renal hemodynamic response
to no-inhibition in healthy humans.
Bech, J. N., C. B. Nielsen, P. Ivarsen, K. T. Jensen, and E. B.
Pedersen.
Research Laboratory of Nephrology and Hypertension, Aarhus
Amtssygehus, University Hospital in Aarhus, Denmark
APStracts 5:0027F, 1998.
Animal studies have indicated that increased nitric oxide (NO)
synthesis plays a significant role in the renal adaptation to
increased sodium intake. To investigate the role of NO during
increased sodium intake in humans, we studied the effect of acute,
systemic injection of NG-monomethyl-L-arginine (L-NMMA) on renal
hemodynamics (GFR and RPF), urinary sodium excretion (FENa), systemic
hemodynamics (MAP, HR) and plasma levels of several vasoactive
hormones in 12 healthy subjects during high (250 mmol/day) and low
(77 mmol/day) sodium intake in a crossover design. The sodium diets
were administered for 5 days before the L-NMMA treatments in
randomized order with a washout period of 9 days between each diet
and L-NMMA treatment. GFR and RPF were measured using the renal
clearance of 51-Cr-EDTA and 125-I-Hippuran by the constant infusion
technique in clearance periods of 30 min. duration. Two baseline
periods were obtained after which L-NMMA was given (3 mg/kg over 10
min.) and the effect of treatment was followed over the next 5
clearance periods. During high sodium intake L-NMMA induced a more
pronounced relative decrease in RPF (P=0.0417,ANOVA), a more
pronounced relative decrease in FENa (P=0.0032, ANOVA) and a more
pronounced relative increase in MAP (P=0.0231, ANOVA). During low
sodium intake the effect of L-NMMA on FENa was abolished. During low
sodium intake, L-NMMA induced a sustained drop in plasma renin (31+/
-5 vs. 25+/-5 [mu]U/ml, P<0.001), which was not seen during high
sodium intake. The data indicate, that increased production of NO is
an important part of the adaptation to increased dietary sodium
intake in healthy humans with respect to renal hemodynamics, sodium
excretion and the secretion of renin.
Received 2 September 1997; accepted in final form 22 January
1998.
APS Manuscript Number F282-7.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 28 January 1998