Role of Prostaglandins in Nitric Oxide-Induced Glial Cell-Mediated Vasodilation in Rat Retina

Figures

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  Figure 1. Involvement of prostaglandins in intravitreal injection of NOR3-induced retinal arteriolar dilation in rats. (A): The upper, middle, and bottom panels show the effect of indomethacin (10 nmol/eye), a cyclooxygenase inhibitor, on changes in retinal arteriolar diameter, mean arterial pressure, and heart rate induced by intravitreal injection of NOR3 (5 nmol/eye), respectively. (B): Bar graph shows the integrated area under the NOR3-induced response curve in retinal arteriole in vehicle- and indomethacin-treated groups. Each point or column with a vertical bar represents the mean ± S.E.M. from five animals. * p < 0.05.

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  Figure 2. Involvement of prostanoid EP2 receptors in intravitreal injection of NOR3-induced retinal arteriolar dilation in rats. (A): The effect of PF-04418948 (20 nmol/eye), a prostanoid EP2 receptor antagonist, on changes in retinal arteriolar diameter induced by intravitreal injection of NOR3 (5 nmol/eye). (B): Bar graph shows the integrated area under the NOR3-induced response curve in retinal arteriole in vehicle- and PF-04418948-treated groups. Each point or column with a vertical bar represents the mean ± S.E.M. from five to six animals. * p < 0.05.

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  Figure 3. Involvement of prostanoid EP2 receptors in intravenous infusion of prostaglandin E2 (PGE2)-induced retinal arteriolar dilation in rats. The upper, middle, and bottom panels show the effect of PF-04418948 (20 nmol/eye) on changes in retinal arteriolar diameter, mean arterial pressure, and heart rate induced by intravenous infusion of PGE2 (0.1–30 µg/kg/min), respectively. Each point with a vertical bar represents the mean ± S.E.M. from three animals. * p < 0.05.

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  Figure 4. Involvement of prostanoid IP receptors in intravitreal injection of NOR3-induced retinal arteriolar dilation in rats. (A): The effect of CAY10441 (10 nmol/eye), a prostanoid IP receptor antagonist, on changes in retinal arteriolar diameter induced by intravitreal injection of NOR3 (5 nmol/eye). (B): Bar graph shows the integrated area under the NOR3-induced response curve in retinal arteriole in vehicle- and CAY10441-treated groups. Each point or column with a vertical bar represents the mean ± S.E.M. from four to five animals.

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  Figure 5. Involvement of prostanoid IP receptors in intravenous infusion of prostaglandin I2 (PGI2)-induced retinal arteriolar dilation in rats. The upper, middle, and bottom panels show the effect of CAY10441 (10 nmol/eye) on changes in retinal arteriolar diameter, mean arterial pressure, and heart rate induced by intravenous infusion of PGI2 (0.03–10 µg/kg/min), respectively. Each point with a vertical bar represents the mean ± S.E.M. from four animals. * p < 0.05.

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  Figure 6. Schema of glial cell-mediated vasodilation mechanisms in the retina. Stimulation of NO on glial cells enhances ryanodine receptor-mediated Ca2+ release and thereby stimulates production of prostaglandin E2 (PGE2) or epoxyeicosatrienoic acids (EETs) in the cells. The released PGE2 and EETs dilate retinal blood vessels through stimulation of the prostanoid EP2 (EP2) receptor and large-conductance Ca2+-activated K+ (BKCa) channels, respectively.