To determine the effects of the serinethreonine kinase inhibitor H-7 on (1) cell junctions and the attached actin-based cytoskeleton in cultured bovine aortic endothelial cells, and (2) outflow facility in living monkeys.Methods: Bovine aortic endothelial cells were cultured by standard techniques. The architecture and distribution of actin filaments, vinculin, and ␤-catenin in bovine aortic endothelial cells were studied by immunolabeling before and after exposure to H-7 at various concentrations and durations. Outflow facility (perfusion) and intraocular pressure (Goldmann tonometer) were determined before and after the intracameral or topical administration of H-7 or a vehicle.Results: In bovine aortic endothelial cells, exposure to H-7 produced a reversible time-and concentrationdependent disruption of actin microfilaments and an alteration in the organization of cell-cell and cell-matrix adhesions. In monkeys, intracameral and topical administration of H-7 dose dependently and reversibly doubled facility, and topical H-7 reduced intraocular pressures.Conclusion: H-7 increases outflow facility in monkeys, probably by inhibiting cell contractility, cytoskeletal support, and cell-cell adhesions in the trabecular meshwork.

Abnormally high resistance to aqueous humor drainage via the trabecular meshwork and Schlemm's canal is highly correlated with the development of primary open-angle glaucoma. Contractility of the actomyosin system in the trabecular cells or inner wall endothelium of Schlemm's canal is an important factor in the regulation of outflow resistance. Cytoskeletal agents, affecting F-actin integrity or actomyosin contractility, or gene therapies, employing over-expression of caldesmon or Rho-A inhibition, can decrease outflow resistance in the drainage pathway. In this review, we discuss the mechanisms underlying these and similar effects on trabecular outflow resistance in living animals and/or in cultured ocular anterior segments from enucleated animal or human eyes.

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