Effects of endothelin-1 on human trabecular meshwork cell contraction. an in vitro cell culture model

Trabecular meshwork (TM) cells are now considered to play an active role in the aqueous outflow mechanism, since 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 intra-ocular pressure control. We propose an in vitro culture model as a method in the study of ET-1-induced human trabecular meshwork (HTM) cell contractility. Experiments were performed on semi-confluent HTM cells (primary cultures established from normotensive human donor eyes) at the 2nd passage with PBS as control, ET-1, sarafotoxin 6c (a selective endothelin B receptor agonist) and Y-27632 (a selective inhibitor of rho-associated kinase). The contractile status of the cells was evaluated by a morphometric analysis of the 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. Our data indicate that image analysis of the HTM cell area can be a reliable method in the study of TM cell contractility, since it utilizes human cells and offers versatile opportunities for the pharmacological evaluation of drugs controlling HTM cell status.