HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Cellini, M. Articles by Campos, E. C. Search for Related Content PubMed PubMed Citation Articles by Cellini, M. Articles by Campos, E. C.

---

EYE

Effects of Endothelin-1 and Flunarizine on Human Trabecular Meshwork Cell Contraction

Department of Surgery and Transplant Section Ophthalmology, Alma Mater Studiorum University of Bologna, Bologna, Italy

To whom requests for reprints should be addressed at ¹ Department of Surgery and Transplant—Section Ophthalmology I, University of Bologna, Via Massarenti, 9, I-40138 Bologna, Italy. E-mail: mauro.cellini{at}unibo.it

Abstract

Trabecular meshwork (TM) cells are now considered to play an active role in the aqueous outflow mechanism because they exhibit smooth muscle–like contractile properties. Endothelin-1 (ET-1), a potent vasoconstrictor peptide, has been proposed to play a role in the local regulation of aqueous outflow and intraocular pressure (IOP) control. We propose an in vitro culture model as a method for the study of ET-1–induced human TM (HTM) cell contractility and for the study of whether pre-incubation with flunarizine, a calcium-channel blocker, can inhibit the action of ET-1. Experiments were performed on semiconfluent HTM cells (primary cultures established from normotensive human donor eyes) at the second passage, with phosphate-buffered saline (PBS) as a control. The contractile status of the cells was evaluated by a morphometric analysis of cell area, assuming that HTM cells in culture are able to reduce their area as a consequence of cytoskeletal contraction, rather than regulatory volume decrease. After incubation with 10 µM ET-1 for 5 mins, we observed a reduction of HTM cell area with respect to PBS-treated cells: 2425 ± 876 µm² versus 3125 ± 987 µm² (P < 0.001); and cells exhibited a retraction in shape and a reduction in number of indented profiles. Administration of ET-1 at progressively lower doses produced a corresponding lower reduction of HTM cell area, suggesting a dose-response effect of ET-1. Pre-incubation with 10 µM flunarizine strongly inhibited the ET-1 effect on HTM cell contraction: 2806 ± 865 µm² versus 2910 ± 846 µm² (P = not significant). Our data indicate that ET-1 induced a statistically significant reduction in the area of HTM cells versus controls, and that ET-1 can directly influence the aqueous outflow. Moreover, we observed that flunarizine inhibited the effect of ET-1 on the HTM cells.

Key Words: HTM cells • morphometric analysis • endothelin-1 • calcium channel blockers • flunarizine • cell contraction