Sumi, Daigo

Endothelial nitric oxide synthase (eNOS) is regulated both by caveolin-1 and 17β-estradiol (E2). Temporal relationships between effects of estrogen on caveolin-1 and nitric oxide (NO) are not known. Therefore, this study was designed to determine whether estrogen regulates caveolin-1 and, if so, whether such regulation corresponds to changes in nitrite/nitrate (NOx) production. Bovine aortic endothelial cells (BAECs) were cultured in the absence and presence of 17β-estradiol or 17α-estradiol (10−8and 10−10M) for 12, 24, and 48 h. eNOS protein expression and NOxproduction increased significantly after 24 h but not after 12-h treatment with 17β- and not 17α-estradiol. Both mRNA and protein for caveolin-1 were increased significantly only after 48-h treatment with E2, but eNOS protein and NOxproduction were decreased compared with cells treated for 24 h. These increases in caveolin-1 were inhibited by the estrogen receptor antagonist ICI-182,780 (10−6M). Results of this study suggest that E2stimulates caveolin-1 transcription and translation through estrogen receptor-mediated mechanisms. The results further suggest that estrogen may indirectly regulate NOxthrough caveolin-1 expression, which inhibits eNOS catalytic activity.

Lower-limb ischemia is a major health problem. Because of the absence of effective treatment in the advanced stages of the disease, amputation is undertaken to alleviate unbearable symptoms. Novel therapeutic approaches include the intramuscular use of autologous bone marrow cells (BMCs). Because tissue ischemia is associated with an overwhelming generation of oxygen radicals and negative effects due to perturbed shear-stress, metabolic intervention with antioxidants and l -arginine could potentially induce beneficial effects beyond those achieved by BMCs. The protective effect of autologous BMCs and vascular protection by metabolic cotreatment (1.0% vitamin E added to the chow and 0.05% vitamin C and 6% l -arginine added to the drinking water) were examined in ischemia-induced angiogenesis in the mouse hindlimb, a model of extensive acute peripheral arterial occlusion. i.v. BMC therapy improved blood flow and increased capillary densities and expression of Ki-67, a proliferation-associated protein. This beneficial effect was amplified by metabolic cotreatment, an intervention inducing vascular protection, at least in part, through the nitric oxide pathway, reduction of systemic oxidative stress, and macrophage activation. Therefore, although a cautious approach is mandatory when experimental findings are extended to human diseases, autologous BMCs together with metabolic intervention could be an effective clinical treatment for peripheral arterial disease.