Prostaglandin induced changes in the tone of porcine retinal arterioles in vitro involve other factors than calcium activity in perivascular cells.

Abstract The cellular basis for the regulation of retinal blood flow is unknown, but recently a new type of perivascular cell (PVC) with pericyte characteristics was identified in the retinal arterial vascular wall located immediately external to the vascular smooth muscle cells. A possible involvement of this cell type in the regulation of retinal vascular tone might be elucidated by studying differences in the response after the addition of compounds stimulating respectively relaxation and contraction. The effects of PGE 2 and PGF 2 α on vascular tone and calcium activity in PVCs in porcine retinal arterioles were studied in a confocal myograph after the addition of the ryanodine receptor blocker ryanodine, the L-type Ca 2+ channel blocker nifedipine, the non-specific cation channel blocker LOE908, the sarcoplasmic reticulum Ca 2+ -ATPase (SERCA) blocker CPA, and the inositol triphosphate receptor (IP 3 R) and transient receptor potential (TRP) ion channel blocker 2-APB. The Ca 2+ channel blockers nifedipine and LOE908 induced significant relaxation of retinal arterioles. After the addition of both PGE 2 and PGF 2 α calcium activity in the PVCs was significantly reduced by both the SERCA inhibitor CPA and the IP 3 R antagonist 2-APB, but the changes in calcium activity were unrelated to the changes in tone induced by PGE 2 and PGF 2 α. Changes in the tone of porcine retinal arterioles in vitro induced by PGE 2 and PGF 2 α involve other factors than calcium activity in the perivascular cells.