Effect of angiotensin II infusion with and without angiotensin II type 1 receptor blockade on nitric oxide metabolism and endothelin in human beings: a placebo-controlled study in healthy volunteers.
BACKGROUND
Angiotensin II has been shown to induce the synthesis of endothelium-derived relaxing factor nitric oxide (NO) and endothelin in vitro. In human beings, to our knowledge, no data on NO release in response to angiotensin II and on the influence of angiotensin II type 1 receptor blockade have been published.


METHODS
In a placebo-controlled study in nine healthy volunteers, angiotensin II was administered intravenously for 6 hours with and without pretreatment with valsartan, a specific angiotensin II type 1 receptor antagonist. NO (NO2 + NO3) and endothelin plasma concentrations, clearance values for inulin and paraaminohippuric acid and NO (NO2 + NO3) excretion in urine were determined.


RESULTS
During angiotensin II infusion NO plasma concentrations remained unaltered compared with placebo after 3 hours: 6.66 +/- 5.49 versus 5.56 +/- 3.09 micromol/L (P = ns) but increased after 6 hours: 18.36 +/- 20.02 versus 7.13 +/- 3.87 micromol/L (P < .04). The same was noted after pretreatment with valsartan: 7.61 +/- 5.69 versus 5.56 +/- 3.09 micromol/L (P= ns) after 3 hours, and 21.70 +/- 11.51 versus 7.13 +/- 3.87 micromol/L (P = .02) after 6 hours. In urine fractional NO excretion decreased after angiotensin II infusion: 0.87 +/- 0.72 versus 0.95 +/- 0.71 (P = .5) during the first 3 hours, and 0.44 +/- 0.39 versus 0.78 +/- 0.43 (P = .01) during the following 3 hours. After valsartan pretreatment the decrease in fractional urinary NO excretion began earlier: 0.40 +/- 0.15 versus 0.95 +/- 0.71 (P = .04) during the first 3 hours, and 0.17 +/- 0.11 versus 0.78 +/- 0.43 (P = .01) during the following 3 hours. Endothelin plasma concentrations showed no difference after angiotensin II infusion with or without valsartan.


CONCLUSIONS
Our observations demonstrate for the first time that angiotensin II increases NO plasma concentrations in human beings and that this response is not mediated by angiotensin II type 1 receptor. In spite of increased NO plasma levels, urinary NO excretion decreased. Endothelin plasma levels remained unchanged during angiotensin II infusion.
Gossmann
J
J
Funktionsbereich Nephrologie, Med. Klinik IV, Abt f Klinische Pharmakologie, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt/Main, Germany. J.Grossmann@em.uni-frankfurt.de
Burkhardt
R
R
Harder
S
S
Lenz
T
T
Sedlmeyer
A
A
Klinkhardt
U
U
Haak
T
T
Geiger
H
H
Scheuermann
E H
EH
D000328:Adult; D000804:Angiotensin II / Q000008:administration & dosage / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D016232:Endothelins / Q000097:blood*; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D009569:Nitric Oxide / Q000097:blood / Q000378:metabolism* / Q000652:urine; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D013777:Tetrazoles / Q000494:pharmacology*; D014633:Valine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000068756:Valsartan
D057911:Angiotensin Receptor Antagonists; D000959:Antihypertensive Agents; D016232:Endothelins; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D013777:Tetrazoles; D000804:Angiotensin II; D009569:Nitric Oxide; D000068756:Valsartan; D014633:Valine