Nitric oxide dependence of renal blood flow in patients with renal artery stenosis.
In ischemia, nitric oxide (NO) production is increased, possibly to preserve flow. The role of NO was investigated in hypertensive patients with or without renal artery stenosis (RAS). Fifty-five hypertensive patients scheduled to undergo diagnostic renal angiography underwent mean renal blood flow (MRBF) measurements before and after an intrarenal injection of the NO synthase blocker N(g)-monomethyl-L-arginine (L-NMMA) at 0.03 microg/kg, before angiography. A dose-response study indicated that this dose of L-NMMA significantly blocked NO synthesis. MRBF was measured at baseline and 1, 5, 10, and 20 min after L-NMMA treatment. On the basis of the angiographic results, patients were divided into three diagnostic categories, i.e., essential hypertension (n = 26), unilateral RAS (n = 16), or bilateral RAS (n = 8). In essential hypertension, MRBF was decreased by 18 +/- 4% at 20 min. In unilateral RAS, L-NMMA did not affect MRBF in the stenotic kidney but reduced MRBF in the nonstenotic kidney by 40 +/- 9% at 20 min. In bilateral RAS, L-NMMA reduced flow by 32 +/- 14% at 20 min. In the nonstenotic kidney in unilateral RAS, a positive correlation was observed between the effect of NO blockade on MRBF and arterial renin levels (P = 0.009). In the stenotic kidney, in contrast, this correlation was inverse (P = 0.007). In conclusion, MRBF depends on NO in hypertensive patients, except in the stenotic kidney in unilateral RAS. In the nonstenotic kidney in unilateral RAS, NO bioavailability is increased. It is suggested that a compensatory mechanism, regulated by NO and possibly angiotensin II, may preserve renal function.
Wierema
Thomas K A
TKA
Department of Internal Medicine, University Hospital Maastricht and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands.
Houben
Alphons J H M
AJHM
Department of Internal Medicine, University Hospital Maastricht and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands.
Kroon
Abraham A
AA
Department of Internal Medicine, University Hospital Maastricht and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands.
Koster
Derk
D
Department of Radiology, University Hospital Maastricht and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands.
Zander
Kim VAN DER
KV
Department of Internal Medicine, University Hospital Maastricht and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands.
Engelshoven
Jos M A VAN
JMAV
Department of Radiology, University Hospital Maastricht and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands.
Leeuw
Peter W DE
PW
Department of Internal Medicine, University Hospital Maastricht and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands.
D000792:Angiography; D000804:Angiotensin II / Q000097:blood; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000502:physiology*; D012016:Reference Values; D012078:Renal Artery Obstruction / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012079:Renal Circulation / Q000502:physiology*; D012083:Renin / Q000097:blood; D012720:Severity of Illness Index; D019323:omega-N-Methylarginine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D000804:Angiotensin II; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D012083:Renin