INHIBITION OF NOS ::
Endogenous inhibitors of NOS such as methylarginine has been suggested to exist and recently it was reported that there is a 10 KDa protein named PIN that is able to destabilize nNOS dimers and hence inhibit enzyme activity in vitro
Properties of NOS isoforms
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Features nNOS NOS iNOS
(neuronal) (constitutive) (inducible)
(endothelial)
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other nomenclature Type 1 Type 3 Type 2
bNOS (brain) cNOS Mac NOS (macrophage) immunological
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Molecular weight 168 KDa 135 KDa 130 KDa
calcium dependency yes yes No
Source NANC neurons Endothelial Macrophages
Skeletal muscle cell Neutrophils
White blood cells Some Hepatocytes
Respiratory and GIT neurones Fibroblasts
epithelia Kidney Chondrocytes
macula densa cells Epithelial cells
Pancreatic islet cells
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Stimulus for Glutamate Acetylcholine Lipopolysaccharide (LPL)
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activation/induction HIV gp-120 Bradykinin Interferon y
b-amyloid peptide Thrombin Cytokines
Shear stress Oxidised LDL
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Amount released Small pulses Small pulses Large continuous
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Function Regulatory Regulatory Host defense
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