| Research Abstract |
Changes in the outflow facility of perfused bovine eyes, in the shape of cultured trabecular meshwork (TM) and in the responses of the bovine ciliary muscles have been studied after exposure to prostaglandins (PGs), adrenergic drugs, hydrogen peroxides and other substances relating insults and intraocular surgery. Bovine TM tissues were isolated and cultured by the method of Crean et al. Cells were monitored by phase-contrast microscopy.
Dobutamine caused confluent TM cells to change from their usual polygonal shape to a characteristic stellate shape. Salbutamol was without effect. The phosphodiesterase (PDE) in hibitors were very effective in producing this shape change. Epinephrine, isoproterenol or salbutamol did not increase the outflow facility. The facility was 97.3(]SY.+-。[)6.8 (1 muM), 80,8(]SY.+-。[)5.9 (10 muM), 80,8(]SY.+-。[)5.9 (10 muM), 83.5(]SY.+-。[)4.7% (100 muM), respectively, in the case of dobutamine, a beta1 agonist. By contrast, H202 increased facility by 46.5(]SY.+-。[)6.5% (with H202) and 22.1 (]SY.+-。[)7.2% (without H202), especially in the presence of 3 amnotriazole (3AT) and BCNU.PGs also increased the facility, especially in the presence of indomethacin.
The high concentrations of beta-adrenergic agents required to produce even a small change in outflow facility, the cell shape and the accompanying response of ciliary muscles argue against the involvement of adrenergic receptor mediation. The mechanism may be alternatively explained different from beta action. PDE inhibition, PGs and/or oxidative stress playd great influence on and around the outflow channels.
So far, there has been no success in demonstrating such an effect on facility of animal eyes in vitro. However, this study suggests a possibility that such biological substances maay reduce outflow facility of the eye in relation to insults or intraocular surgery, possibly causing untreatable glaucoma.
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