[Effects of beta-adrenergic agonists and phosphodiesterase inhibitors on the outflow facility of the eye].
Changes in the outflow facility of perfused bovine eyes and in the shape of cells in cultured trabecular meshwork (TM) were studied after exposure to adrenergic drugs. Dobutamine, a selective beta 1 agonist caused confluent TM cells to change from their usual polygonal shape to a characteristic stellate shape. Salbutamol, a selective beta 2 agonist showed no effect. The phosphodiesterase (PDE) inhibitors, isobutylmethylxanthine (IBMX), theophylline, and caffeine were also very effective in producing this shape change. Epinephrine, isoproterenol, dobutamine or salbutamol did not increase the outflow facility, at temperatures of 22 degrees C or 36 degrees C, whereas theophylline, caffeine and IBMX increased the facility in a dose-dependent manner. The high concentrations of beta-adrenergic agents required to produce even a small change in outflow facility and the cell shape argue against the involvement of adrenergic receptor mediation; on the other hand, the enhancement of the effects of epinephrine by PDE inhibitors and a similar effect produced by cAMP suggest that the changes in the cell shape are produced by beta-receptor activation. The beta-adrenergic agents were ineffective on changing outflow facility but the PDE inhibitors were remarkably effective in producing both shape change and increasing facility. PDE inhibition has much greater influence on and around the outflow channels than pure beta-adrenergic agonists, at least in enucleated bovine eyes.
Suzuki
R
R
Department of Ophthalmology, Yamaguchi University School of Medicine, Japan.
Fujikura
Y
Y
Anderson
P J
PJ
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000420:Albuterol / Q000494:pharmacology; D000818:Animals; D001082:Aqueous Humor / Q000187:drug effects* / Q000502:physiology; D002110:Caffeine / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D004280:Dobutamine / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D013806:Theophylline / Q000494:pharmacology; D014129:Trabecular Meshwork / Q000166:cytology / Q000187:drug effects*
D000318:Adrenergic beta-Agonists; D010726:Phosphodiesterase Inhibitors; D002110:Caffeine; D004280:Dobutamine; D013806:Theophylline; D007545:Isoproterenol; D000420:Albuterol; D015056:1-Methyl-3-isobutylxanthine; D004837:Epinephrine