Regulation of trabecular meshwork contractility

Ample evidence supports the theory that trabecular meshwork possesses smoot h-muscle-like properties. Trabecular meshwork cells express a large number of transporters, channels and receptors, many of which are known to regulat e smooth-muscle contractility. It has been shown that trabecular meshwork c an be induced to contract and relax in response to pharmacological agents. In the model of the bovine eye, confirmed in some cases by experiments on p rimates, agents that contract trabecular meshwork reduce outflow, On the ce llular level, this is coupled with depolarization and a rise in intracellul ar calcium. Relaxation of trabecular meshwork, on the other hand, appears t o be coupled to a stimulation of the maxi-K channel, inducing hyperpolariza tion and a closure of L-type calcium channels. No significant differences b etween cells from a human and a bovine source emerged, either in classical measurements of membrane voltage, in measurements of intracellular calcium or patch-clamp experiments. Thus, pharmacological agents that relax trabecu lar meshwork seem promising candidates for further research - the ultimate goal being an improvement of glaucoma therapy in humans. Copyright (C) 2000 S. Karger AG. Basel.