Extracellular l-arginine Enhances Relaxations Induced by Opening of Calcium-Activated SKCa Channels in Porcine Retinal Arteriole

Figures

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  Figure A1. l-arginine-induced relaxation in the absence and presence of CyPPA (6 µM), an opener of SKCa2 and SKCa3 channels, or ADMA (300 µM), an inhibitor of NO synthase, in U46619-contracted porcine retinal arterioles. Data are means ± S.E.M. (n = 5–7). Two-way ANOVA. * p < 0.05 vs. control.

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  Figure A2. Bradykinin-induced relaxation in the absence and presence of l-arginine (100 µM) and CyPPA (6 µM), an activator of SKCa2-3 channels, in U46619-contracted porcine retinal arterioles. Data are means ± S.E.M. (n = 6–7). Two-way ANOVA. * p < 0.05 vs. control.

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  Figure 1. 3H-l-arginine uptake in rat aortic valve endothelial cells in the absence and presence of the combination of apamin (0.5 µM), a SKCa channel blocker, and charybdotoxin (ChTX, 0.1 µM), an IKCa channel blocker, and of l-lysine (600 µM), both inhibiting l-arginine uptake through the CAT system, and of low Na+-PSS which inhibits L-arginine uptake through the Na+-dependent (Bo,+) CAT system. Data are means ± S.E.M. (n = 6). One-way ANOVA. # p < 0.05 vs. baseline. * p < 0.05 vs. control.

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  Figure 2. Representative images showing immunoreaction for (A) eNOS, (B) smooth muscle actin, and (C) merged immunoreaction for eNOS and smooth muscle actin, and (D) no co-localization of eNOS and smooth muscle actin. Immunoreaction for (E) eNOS, (F) SKCa3, and (G) merged immunoreaction for eNOS and SKCa3, and (H) co-localization in blue of eNOS and SKCa3. Immunoreaction for (I) eNOS, (J) CAT-1, and (K) merged immunoreaction for eNOS and CAT-1, and (L) co-localization in blue of eNOS and CAT-1.

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  Figure 3. Activation of SKCa currents in porcine arterial endothelial cells by CyPPA. (A) Representative whole-cell currents in the absence (w/o) and in the presence of CyPPA (10 µM) as well as inhibition of the CyPPA-activated currents by the SKCa blocker, UCL-1684 (1 µM). (B) Average data are given as means ± S.E.M. (CyPPA, n = 4; UCl1684, n = 3); * p < 0.05 vs. w/o; # p < 0.05 vs. CyPPA.

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  Figure 4. Pharmacological modulation of myogenic tone in porcine retinal arteries by (A) an opener of SKCa channels, CyPPA (6 µM, n = 6), an inhibitor of NO synthase, asymmetric dimethylarginine (ADMA, 100 µM, n = 7), and a blocker of SKCa channels, apamin (0.5 µM, n = 8) and by (B) substrate for NO synthase, l-arginine (100 µM, n = 9), and l-arginine in the presence of blockers of the y+ transporter, l-lysine (600 µM, n = 9) or low Na+-PSS (n = 9). Data are means ± S.E.M. * p < 0.05 vs. control.

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  Figure 5. Modulation of CyPPA-induced relaxation in porcine retinal arterioles by (A) ADMA (300 µM), an inhibitor of NO synthase, apamin (0.5 µM), a blocker of SKCa channels, by (B) l-arginine (100 µM), l-lysine (600 µM), and low Na+-PSS. Data are means ± S.E.M. (n = 7–9). Two-way ANOVA. * p < 0.05 vs. control.