NADPH oxidase accounts for enhanced superoxide production and impaired endothelium-dependent smooth muscle relaxation in BKbeta1-/- mice.
OBJECTIVE
Nitric oxide (NO)-induced vasorelaxation involves activation of large conductance Ca2+-activated K+ channels (BK). A regulatory BKbeta1 subunit confers Ca2+, voltage, and NO/cGMP sensitivity to the BK channel. We investigated whether endothelial function and NO/cGMP signaling is affected by a deletion of the beta1-subunit.


RESULTS
Vascular superoxide in BKbeta1-/- was measured using the fluorescent dye hydroethidine and lucigenin-enhanced chemiluminescence. Vascular NO formation was analyzed using electron paramagnetic resonance (EPR), expression of NADPH oxidase subunits, the endothelial NO synthase (eNOS), the soluble guanylyl cyclase (sGC), as well as the activity and expression of the cyclic GMP-dependent kinase I (cGK-I) were assessed by Western blotting technique. eNOS, sGC, cGK-I expression and acetylcholine-induced NO production were unaltered in Bkbeta1-/- animals, whereas endothelial function was impaired and the activity of the cGK-I was reduced. Vascular O2- and expression of the NADPH oxidase subunits p67phox and Nox1 were increased. Endothelial dysfunction was normalized by the NADPH oxidase inhibitor apocynin. Potassium chloride- and iberiotoxin-induced depolarization mimicked the effect of BKbeta1-deletion by increasing vascular O2- in an NADPH-dependent fashion.


CONCLUSIONS
The deletion of BKbeta1 causes endothelial dysfunction by increasing O2- formation via increasing activity and expression of the vascular NADPH oxidase.
Oelze
Matthias
M
II.Medizinische Klinik, Johannes Gutenberg-Universität Mainz, Langenbeckstrasse 1, D-55131 Mainz, Germany.
Warnholtz
Ascan
A
Faulhaber
Jörg
J
Wenzel
Philip
P
Kleschyov
Andrei L
AL
Coldewey
Meike
M
Hink
Ulrich
U
Pongs
Olaf
O
Fleming
Ingrid
I
Wassmann
Sven
S
Meinertz
Thomas
T
Ehmke
Heimo
H
Daiber
Andreas
A
Münzel
Thomas
T
D000818:Animals; D001013:Aorta, Thoracic / Q000503:physiopathology; D015815:Cell Adhesion Molecules / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism; D004730:Endothelium, Vascular / Q000503:physiopathology*; D006162:Guanylate Cyclase / Q000378:metabolism; D006801:Humans; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000172:deficiency*; D051379:Mice; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis / Q000494:pharmacology; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D020033:Protein Isoforms / Q000172:deficiency; D015398:Signal Transduction; D013481:Superoxides / Q000378:metabolism*; D014664:Vasodilation; D000098662:Vasodilator-Stimulated Phosphoprotein
D015815:Cell Adhesion Molecules; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008840:Microfilament Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; C079789:neutrophil cytosol factor 67K; D000098662:Vasodilator-Stimulated Phosphoprotein; D013481:Superoxides; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases; C000614711:NOX1 protein, mouse; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase