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- Title
Effects of angiotensin II on renal sodium handling and diluting capacity in man pretreated with high-salt diet and enalapril.
- Authors
Vos, P. F.; Koomans, H. A.; Boer, P.; Dorhout Mees, E. J.
- Abstract
The antinatriuretic effect of angiotensin II (Ang II) is generally attributed to a decreased glomerular filtration rate (GFR) and an increased proximal tubular sodium reabsorption. We studied this by infusion of increasing amounts (1, 4, and 8 pmol/kg per min) of Ang II in seven water-loaded volunteers who were pretreated with enalapril and a high-salt diet. While mean arterial pressure increased from 92±3mmHg to respectively 98±3, 110±2, and 116±2mmHg, sodium excretion fell from 331±40 to 135±23, 65±17, and 63±22 μmol/min, and GFR from 138±9 to 128±6, 111±6, and 104±8 ml/min (<0.05 for each variable). At 1 pmol/kg per min, Ang II decreased maximal urine flow and the fractional excretions of lithium and uric acid. Urine sodium concentration decreased, whereas minimal urine osmolality remained unchanged. At 4 pmol/kgper min, these effects were more pronounced. Moreover, minimal urine osmolality increased from 58±4 to 72±8 mosm/kg, but sodium concentration decreased further. The step to 8 pmol/kg per min did not decrease sodium, lithium, or uric acid excretion further, but induced a further increase in minimal urine osmolality to 99±16 mosm/kg. These data suggest that the antinatriuretic effect of modestly hypertensive dosages of Ang II is not only due to a decrease in GFR and an increase in proximal sodium reabsorption, but also involves a rise in fractional reabsorption in a distal nephron segment. In addition Ang II decreases renal diluting capacity. Whether these effects on the distal nephron concern a direct Ang II–tubule interaction or are mediated indirectly remains to be clarified.
- Publication
Nephrology Dialysis Transplantation, 1992, Vol 7, Issue 10, p991
- ISSN
0931-0509
- Publication type
Article