Relaxing effect of CEDO 8956 and hydralazine HCl in cultured smooth muscle cells versus pericytes: A preliminary study

Background: It hs been reported that some glaucoma patients have deficient endothelial nitric oxide production. The effect of the presupposed nitrovasodilators CEDO 8956 and hydralazine hydrochloride (HCl) on bovine retinal microcirculation pericytes and ophthalmic artery smooth muscle cells are investigated. Methods: Cells were cultured on silicone membranes and their contractile tone observed by phase contrast inverted microscopy before and after exposure by fluid exchange to different drugs at various concentrations. Experiments were conducted with pericytes in the absence (control) or in the presence (10nM-0.1 mM) of CEDO 8956, hydralazine HCl, or sodium nitroprusside (SNP). Experiments were conducted with smooth muscle cells in the absence (control) or in the presence (0.1 mM) of CEDO 8956, or hydralazine HCl. Results: In comparison to control (-0.56 ± 10%), pericytes were significantly relaxed by SNP (100 ± 0%, p < 0.001), but not by CEDO 8956 (9.2 ± 15.4%) or hydralazine HCl (20.6 ± 4.4%). In comparison to control (1.64 ± 5.3%), smooth muscle cells were significantly relaxed by CEDO 8956 (46.2 ± 12.4%, p < 0.05) and hydralazine HCl (54.9 ± 9.1%, p < 0.001). Conclusions: These results suggest a possible heterogeneity between cultured bovine microcirculation pericytes and ophthalmic artery vascular smooth muscle cells in the relaxing response to CEDO 8956 and hydralazine HCl. Apparently, these two drugs might not be first choice candidates in order to attempt to try to selectively improve circulation in the retina or the optic nerve head capillary network.