Reversal of endothelial nitric oxide synthase uncoupling and up-regulation of endothelial nitric oxide synthase expression lowers blood pressure in hypertensive rats.
OBJECTIVE
We sought to examine the hypothesis that a pharmacologic up-regulation of endothelial nitric oxide synthase (eNOS) combined with a reversal of eNOS uncoupling provides a protective effect against cardiovascular disease.


BACKGROUND
Many cardiovascular diseases are associated with oxidant stress involving protein kinase C (PKC) and uncoupling of eNOS.


METHODS
Messenger ribonucleic acid (mRNA) expression was analyzed with RNase protection assay or quantitative real-time polymerase chain reaction, vascular nitric oxide (NO) with spin trapping, and reactive oxygen species (ROS) with dihydroethidium fluorescence.


RESULTS
Aortas of spontaneously hypertensive rats (SHR) showed an elevated production of ROS when compared with aortas of Wistar-Kyoto rats (WKY). The aortic expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits (Nox1, Nox2, Nox4, and p22phox) was higher in SHR compared with WKY. In SHR, aortic production of ROS was reduced by the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME), indicating eNOS "uncoupling" in hypertension. Oral treatment with the PKC inhibitor midostaurin reduced aortic Nox1 expression, diminished ROS production, and reversed eNOS uncoupling in SHR. Aortic levels of (6R)-5,6,7,8-tetrahydro-L-biopterin (BH4) were significantly reduced in SHR compared with WKY. Midostaurin normalized BH4 levels in SHR. In both WKY and SHR, midostaurin increased aortic expression of eNOS mRNA and protein, stimulated bioactive NO production, and enhanced relaxation of the aorta to acetylcholine. Midostaurin lowered blood pressure in SHR and, to a lesser extent, in WKY; the compound did not change blood pressure in WKY made hypertensive with L-NAME.


CONCLUSIONS
Pharmacologic interventions that combine eNOS up-regulation and reversal of eNOS uncoupling can markedly increase bioactive NO in the vasculature and produce beneficial hemodynamic effects such as a reduction of blood pressure.
Li
Huige
H
Department of Pharmacology, Johannes Gutenberg University, Mainz, Germany. HuigeLi@mail.Uni-Mainz.de
Witte
Klaus
K
August
Michael
M
Brausch
Isolde
I
Gödtel-Armbrust
Ute
U
Habermeier
Alice
A
Closs
Ellen I
EI
Oelze
Mathias
M
Münzel
Thomas
T
Förstermann
Ulrich
U
D000818:Animals; D004730:Endothelium, Vascular / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D006973:Hypertension / Q000201:enzymology* / Q000517:prevention & control*; D008297:Male; D019001:Nitric Oxide Synthase / Q000378:metabolism* / Q000502:physiology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D019311:Staurosporine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D015854:Up-Regulation
D004791:Enzyme Inhibitors; D019001:Nitric Oxide Synthase; D011493:Protein Kinase C; D019311:Staurosporine; C059539:midostaurin