Department of Ophthalmology, Aarhus University Hospital, Aarhus C, Denmark.
Invest Ophthalmol Vis Sci. 2013 May 7;54(5):3258-64. doi: 10.1167/iovs.13-11685.
Relaxation of porcine retinal arterioles in vitro has been shown to be preceded by calcium activity in a population of perivascular cells that cannot be classified as neurons, glial cells, or vascular smooth muscle cells. The purpose of the present investigation was to study calcium activity in these perivascular cells during ATP- and PGE2-induced vasorelaxation, and to identify pericyte markers and other cellular constituents characterizing these cells.
Porcine arterioles were loaded with a calcium-sensitive fluorophore and mounted in a myograph. Simultaneous measurements of calcium activity and vascular tone during stimulation with ATP and PGE2 were performed before and after addition of specific antagonists to these compounds and to nitric oxide. Additionally, immunohistochemistry was performed on whole mounts of porcine retina using antibodies to known markers of vascular pericytes and cellular components of the vascular wall.
Relaxation of retinal arterioles with both ATP and PGE2 was preceded by a significant increase in the number of perivascular cells displaying calcium activity. The effect of ATP was inhibited by the adenosine receptor antagonist 8-PSPT, whereas the effect of PGE2 was inhibited by the EP1 receptor antagonist SC19220 and the NO-synthesis inhibitor L-NAME. The perivascular cells had morphological features in common with pericytes and displayed immunoreactivity to the pericyte markers NG2 and CD-13, but not to markers of glial cells, neurons, or vascular smooth muscle cells.
The perivascular cell type located external to the smooth muscle cells in porcine retinal arterioles shows calcium activity during relaxation with ATP and PGE2 and has morphological properties in common with pericytes. Future studies should focus on the role of this cell type for regulating retinal blood flow and for retinal vascular disease.
已证明体外猪视网膜小动脉的松弛先于血管周围细胞群中的钙活动，这些细胞不能归类为神经元、神经胶质细胞或血管平滑肌细胞。本研究的目的是研究在 ATP 和 PGE2 诱导的血管舒张过程中这些血管周围细胞中的钙活性，并鉴定出这些细胞的周细胞标记物和其他细胞成分。
将钙敏感荧光染料加载到猪小动脉中，并安装在肌动描记器中。在添加这些化合物和一氧化氮的特异性拮抗剂前后，同时进行刺激期间的钙活性和血管张力的测量。此外，使用已知的血管周细胞和血管壁细胞成分的标记物抗体对猪视网膜的全培养物进行免疫组织化学染色。
ATP 和 PGE2 引起的视网膜小动脉舒张均先于显示钙活性的血管周围细胞数量显著增加。ATP 的作用被腺苷受体拮抗剂 8-PSPT 抑制，而 PGE2 的作用被 EP1 受体拮抗剂 SC19220 和 NO 合成抑制剂 L-NAME 抑制。这些血管周围细胞具有与周细胞共有的形态特征，并对周细胞标记物 NG2 和 CD-13 具有免疫反应性，但对神经胶质细胞、神经元或血管平滑肌细胞的标记物没有反应。
位于猪视网膜小动脉平滑肌细胞外部的血管周围细胞类型在 ATP 和 PGE2 松弛期间显示钙活性，并且具有与周细胞共有的形态特性。未来的研究应集中于这种细胞类型在调节视网膜血流量和视网膜血管疾病中的作用。
