Histamine-Induced Dilation of Isolated Porcine Retinal Arterioles: Role of Endothelium-Derived Hyperpolarizing Factor.

Purpose: Although endothelium-dependent nitric oxide (NO)-mediated dilation of retinal arterioles has been well described, the role of endothelium-derived hyperpolarizing factor (EDHF) in the retinal arteriolar response remains unclear. In the current study, we examined the contribution of EDHF to the retinal arteriolar dilation to the inflammatory agent histamine and investigated the signaling mechanisms underlying this vasomotor activity.

Methods: Porcine retinal arterioles were isolated, cannulated, and pressurized without flow for functional study by using video microscopic techniques.

Vasodilatory mechanisms of unoprostone isopropyl in isolated porcine retinal arterioles.

Purpose: To clarify the vasodilatory mechanism of unoprostone isopropyl (UI), we examined its effects on the retinal microvascular diameter to determine the dependence on the endothelium and/or smooth muscle to reveal the signaling mechanisms involved in this vasomotor activity.

Methods: Porcine retinal arterioles were isolated, cannulated, and pressurized without flow in vitro. Video microscopic techniques recorded the diametric responses to UI.

Beraprost sodium, a stable prostacyclin analogue, elicits dilation of isolated porcine retinal arterioles: roles of eNOS and potassium channels.

Purpose: Prostacyclin (PGI2) is usually described as an endoEDRFsthelium-derived relaxing factor, but the vasoreactivity to PGI2 in the retinal arterioles and the underlying mechanisms are not fully understood. We examined the effects of PGI2 on the retinal microcirculation using beraprost sodium (BPS), a stable PGI2 analogue, and the signaling mechanisms involved in this vasomotor activity.

Methods: Porcine retinal arterioles were isolated, cannulated, and pressurized without flow in vitro.

Role of Ca2+ -dependent and Ca2+ -sensitive mechanisms in sphingosine 1-phosphate-induced constriction of isolated porcine retinal arterioles in vitro.

Although sphingosine 1-phosphate (S1P), a bioactive lipid derived from activated platelets, has a variety of physiologic effects on vessels, no reports have described the effect of S1P on the retinal circulation. We examined the effect and underlying mechanism of the vasomotor action of S1P on porcine retinal arterioles. The porcine retinal arterioles were isolated, cannulated, and pressurized without flow for in vitro study.

Adiponectin-induced dilation of isolated porcine retinal arterioles via production of nitric oxide from endothelial cells.

Purpose: Adiponectin, an important adipocytokine secreted by adipocytes, has anti-inflammatory and atheroprotective effects on vascular tissue via the adiponectin receptor (adipoR). However, the action of adiponectin in the retinal microcirculation is unknown. We examined the direct effect and underlying mechanism of the vasomotor action of adiponectin in porcine retinal arterioles.

Homocysteine inhibition of endothelium-dependent nitric oxide-mediated dilation of porcine retinal arterioles via enhanced superoxide production.

Purpose: Elevated plasma concentration of homocysteine, a sulfur-containing amino acid, is an emerging risk factor for cardiovascular diseases. Recent epidemiologic studies have confirmed that elevated homocysteine levels are associated with ocular vascular diseases; however, the direct effect of homocysteine on ocular microvascular reactivity remains unknown. We investigated whether homocysteine affects endothelium-dependent nitric oxide (NO)-mediated dilation of retinal arterioles and whether oxidative stress and distinct protein kinase signaling pathways are involved in the homocysteine-mediated effect.

Dilation of porcine retinal arterioles to cilostazol: roles of eNOS phosphorylation via cAMP/protein kinase A and AMP-activated protein kinase and potassium channels.

Purpose: Cilostazol, a selective inhibitor of phosphodiesterase 3, has antiplatelet aggregation and peripheral vasodilation effects. We examined the effects of cilostazol on the retinal microvascular diameter to determine its dependence on the endothelium and/or smooth muscle to reveal the signaling mechanisms involved in this vasomotor activity.

Methods: Porcine retinal arterioles were isolated, cannulated, and pressurized without flow in vitro.

Impaired systemic vascular endothelial function in patients with branch retinal vein occlusion.

Purpose: To evaluate systemic endothelial function in patients with branch retinal vein occlusion (BRVO).

Methods: Twenty-seven patients with BRVO (BRVO group, 8 men, 19 women; mean age, 65.4 ± 1.

Fenofibrate, an anti-dyslipidemia drug, elicits the dilation of isolated porcine retinal arterioles: role of nitric oxide and AMP-activated protein kinase.

Purpose: Although recent clinical trials have demonstrated that fenofibrate is effective for treating diabetic retinopathy, the mechanism of this beneficial effect remains unclear. In the current study, we examined the effect of the vasomotor action of fenofibrate on porcine retinal arterioles.

Methods: Porcine retinal arterioles (internal diameter, 60-90 μm) were isolated, cannulated, and pressurized (55 cmH(2)O) without flow in vitro.

Relationship between choroidal thickness and choroidal circulation in healthy young subjects.

Purpose: To investigate the relationship between the choroidal thickness and choroidal blood flow in healthy young subjects.

Design: Retrospective, cross-sectional study.

Methods: We examined 25 eyes of 25 healthy young Japanese subjects.

Pioglitazone, a peroxisome proliferator-activated receptor-γ agonist, induces dilation of isolated porcine retinal arterioles: role of nitric oxide and potassium channels.

Purpose: Pioglitazone, a peroxisome proliferator-activated receptor (PPAR)-γ agonist, has anti-inflammatory and atheroprotective effects on vascular tissue and may reduce cardiovascular risk in patients with diabetes. The effect of pioglitazone on the retinal microvascular diameter was examined, and it was determined whether the effect depends on the endothelium and/or potassium channels in smooth muscle to reveal the signaling mechanisms involved in this vasomotor activity.

Methods: Porcine retinal arterioles were isolated, cannulated, and pressurized without flow in vitro.