controlled study nitric oxide nonhuman 40 priority journal 40 article 36 nitric oxide synthase 34 Animals 32 animal tissue 30 animal experiment 26 enzyme activity 26 Nitric Oxide Synthase 24 Nitric Oxide 22 male 22 female 20 rat 18 Female 16 Male 16 animal cell 16 Rats 14 mouse 14 protein expression 14 Nitric oxide 12 animal model 12 enzyme activation 12 signal transduction 12 Enzyme Inhibitors 10 Mice 10 arginine 10 nitric oxide synthase inhibitor 10 unclassified drug 10