However, the increased production of NO by iNOS, primed by inflammatory cytokines, leads to an S-nitrosylation of reactive cysteine in
DDAH, inhibiting ADMA catabolism, thus increasing its levels and lastly inhibiting all three isoforms of NOS [26].
Hyperglycemia in type 2 diabetic patients impairs an enzyme,
DDAH which is responsible for the degradation of ADMA, thus leading to high concentration of ADMA in blood8.
In humans,
DDAH exists as two isoforms, DDAH1 and DDAH2.
DDAH activity in diabetic neuropathy patients should be examined in further clinical studies.
Homocysteine induced accumulation of asymmetric dimethylarginine: role of
DDAH and effect of antioxidants.
ADMA is primarily metabolized to citrulline and dimethylamine by the enzyme dimethylaminohydrolase (
DDAH), which has high activity in the liver and kidneys [69-71].
EFFECTS OF TOBACCO SMOKE ON ADMA LIBERATION AND
DDAH EXPRESSION IN EAhy 926 CELLS
ADMA, the endogenous NO inhibitor, also increases in dyslipidemia probably due to inhibition of dimethyl diamino hydrolase (
DDAH) which is the enzyme responsible for ADMA catabolism because of low grade chronic inflammation.
Unchanged ADMA is excreted by the kidneys, but the greatest part of endogenously produced ADMA (about 90%) is excreted in the urine as dimethylamine (DMA) after hydrolysis by the enzyme dimethylarginine dimethylaminohydrolase (
DDAH) [15], predominantly in kidney and liver.
Wild type (WT) C57BL/6 and dimethylarginine dimethylaminohydrolase transgenic (DDAH-I) mice on the C57BL/6 strain that overexpress
DDAH were originally obtained from The Jackson Laboratory (Bar Harbor, ME) and subsequently bred and maintained in microisolator units in the UNMC specific pathogen-free animal facility.
Dimethylamine dimethylaminohydrolase (
DDAH) converts ADMA to citrulline and dimethylamine.