We have shown previously that diabetes causes increases in retinal arginase activity that are associated with impairment of endothelial cell (EC)-dependent vasodilation and increased formation of the peroxynitrite biomarker nitrotyrosine. Arginase blockade normalizes vasodilation responses and reduces nitrotyrosine formation, suggesting that overactive arginase contributes to diabetic retinopat...

Recently, arginase is suggested to regulate nitric oxide production by competing with nitric oxide synthase for the same substrate, L-arginine, in experimental asthma. We investigated the role of arginase and its relationship to nitric oxide production after spinal cord injury. Rats were subjected to laminectomy and complete transection of their spinal cords (injury group) or laminectomy only (...

Background Leukocytes linked directly and indirectly to reactive oxygen species (ROS) formation. Although leukocytospermia is defined as the presence of ≥1×106 white blood cells/mL (WBC/mL) in a semen sample, the presence of less than 1×106 WBC/mL (low-level leukocytospermia) still can produce a detectable amount of ROS, impairing sperm function and lowering the chances of pregnancy. Low concen...

Solid tumors can often be hypoxic in regions, and cancer cells can respond to hypoxia with an increase in proliferation and a decrease in apoptosis, leading to a net increase in viable cell numbers. We have recently found that in an osteosarcoma cell line, hypoxia-induced proliferation depends on arginase II induction. Epidermal growth factor receptor (EGFR) has been shown to mediate the hypoxi...

Consumption of L-arginine contributes to reduced bioavailability of nitric oxide (NO) that is critical for the development of ischemia-reperfusion injury. The aim of the study was to determine myocardial arginase expression and activity in ischemic-reperfusion myocardium and whether local inhibition of arginase within the ischemic myocardium results in increased NO production and protection aga...

BACKGROUND Although abnormal L-arginine NO signaling contributes to endothelial dysfunction in the aging cardiovascular system, the biochemical mechanisms remain controversial. L-arginine, the NO synthase (NOS) precursor, is also a substrate for arginase. We tested the hypotheses that arginase reciprocally regulates NOS by modulating L-arginine bioavailability and that arginase is upregulated i...

RATIONALE Airway nitric oxide concentrations are reduced in cystic fibrosis (CF). Arginases compete for L-arginine, the substrate of nitric oxide synthesis. OBJECTIVES We hypothesized that increased arginase activity may be one factor contributing to nitric oxide deficiency in CF. MEASUREMENTS We therefore studied sputum arginase activity, exhaled nitric oxide, and pulmonary function in pat...

Differential and sucrose density gradient centrifugation established that about 80% of the total arginase activity (EC 3.5.3.1) in cotyledons of germinating broad bean seeds (Vicia faba L.) was present in the mitochondrial fraction. The mitochondrial arginase activity was enhanced considerably by exposure to osmotic shock, by freezing and thawing, or by Triton X-100 treatment. About 10% of the ...

N EXTENSIVE LITERATURE Ofl arginase activity in tissues and tissue homogenates has accumulated in recent years. Roberts (1) has studied the arginase activity of liver, kidney, and epidermis of the Swiss mouse and of a transplantable squamous cell carcinoma. He found that liver had the greatest activity, followed by carcinoma, epidermis, and kidney. Sano (2) isolated an enzyme from rabbit intest...

BACKGROUND Arginase competes with endothelial nitric oxide synthase (eNOS) for the substrate l-arginine and decreases NO production. This study investigated regulatory mechanisms of arginase activity in endothelial cells and its role in atherosclerosis. METHODS AND RESULTS In human endothelial cells isolated from umbilical veins, thrombin concentration- and time-dependently stimulated arginas...