Fig. 4.

NOX1, NOX2, p47phox, or NOX4 knockout improved NO and H₄B bioavailabilities, reduced superoxide production, and recoupled eNOS in Ang II infused hph-1 mice. (A) Aortic nitric oxide (NO) production was determined from aortic segments using electron spin resonance (ESR). Double mutants of hph-1 with NOX1, NOX2, p47phox, or NOX4 corrected the decline in aortic NO production in Ang II-infused hph-1 animals. n=4, *p<0.05, **p<0.01. (B) Total superoxide production was measured from aortic homogenates using ESR. eNOS uncoupling activity was assessed by comparing measurements with and without the addition of L-NAME, a NOS inhibitor, n=4–7, *p<0.05. A reduction in superoxide production with L-NAME indicates that NOS is uncoupled and producing superoxide. The eNOS uncoupling phenotype in hph-1 mice was prevented in all of the double mutant mice. (C) Aortic H₄B bioavailability was determined by HPLC, and the deficiency of H₄4B in hph-1 mice was corrected in all of the double mutant mice. n=5, *p<0.05, **p<0.01.