January 1999
Volume 40, Issue 1
Free
Articles  |   January 1999
Acto-myosin drug effects and aqueous outflow function.
Author Affiliations
  • D L Epstein
    Department of Ophthalmology, Duke University Medical Center, Duke University Eye Center, Durham, North Carolina 27710, USA.
  • L L Rowlette
    Department of Ophthalmology, Duke University Medical Center, Duke University Eye Center, Durham, North Carolina 27710, USA.
  • B C Roberts
    Department of Ophthalmology, Duke University Medical Center, Duke University Eye Center, Durham, North Carolina 27710, USA.
Investigative Ophthalmology & Visual Science January 1999, Vol.40, 74-81. doi:
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    • Get Citation

      D L Epstein, L L Rowlette, B C Roberts; Acto-myosin drug effects and aqueous outflow function.. Invest. Ophthalmol. Vis. Sci. 1999;40(1):74-81.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

PURPOSE: Previous studies have identified the cytoskeletal proteins actin and tubulin as potential cellular targets in the trabecular meshwork for novel glaucoma therapy. The authors and others have hypothesized that acto-myosin interactions may be important for outflow function. The current study was conducted to evaluate 2,3-butanedione 2-monoxime (BDM), a compound that interferes with acto-myosin function through the myosin adenosine triphosphatase (ATPase) reaction; 1-(5-isoquinolinylsulfonyl)-2-methyl-piperazine (H-7), a proposed myosin light-chain kinase inhibitor; and the direct actin disrupter, latrunculin B, in an outflow pathway cell culture and perfused excised eye model system. METHODS: Freshly enucleated porcine eyes were perfused using the constant-pressure method at 15 mm Hg and 25 degrees C. Human trabecular meshwork (HTM) cells and Schlemm's canal (SC) cells were grown in culture, treated with BDM, H-7, and latrunculin B, and then fixed, stained for beta-tubulin and filamentous actin, and observed by epifluorescence. RESULTS: Twenty millimolar BDM, 100 microM H-7, and 1 microM latrunculin B increased outflow facility 36%, 63%, and 72%, respectively, compared to sham-treated controls, 13%, 15%, and 4% (n=7, 8, and 8; P=0.01, 0.0001, and 0.0002), respectively. In cultured HTM and SC cells, 100 microM H-7 caused a rapid loss of filamentous actin staining but did not produce a change in cell shape or cell- cell attachment. In contrast, 20 mM BDM induced a loss of cell- cell attachment and a change in cell shape that was associated with a 50% to 60% loss of filamentous actin staining, often in a distinct stick-and-ball pattern. Latrunculin B caused a severe loss of actin staining and cell shape changes. No drug altered beta-tubulin staining. CONCLUSIONS: Interference with myosin function can cause a secondary loss of actin organizational structure. Our study indicates that myosin, perhaps through its various phosphorylation reactions, may have a potential regulatory role in outflow function.

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