Abstract
Trabecularf2f2Parts of this work were published in abstract form: Steinhausen, K., Stumpff, F., Strauß, O., Wiederholt, M. 1998. Trabecular meshwork cells express L-type Ca2+channels. Pflügers Arch. 437 (Suppl.): R79.meshwork (TM), a smooth muscle-like tissue with contractile properties, is involved in the regulation of aqueous humor outflow. However, little is known about the regulation of Ca2+influx in trabecular meshwork cells. We investigated the influence of acetylcholine and tyrosine kinases on Ca2+conductances of bovine TM (BTM) and human TM (HTM) cells using the perforated-patch configuration of the patch-clamp technique and measurements of intracellular free Ca2+([Ca2+]i). Depolarization of the cells in the presence of 10 m m Ba2+or Ca2+led to an activation of inward currents at potentials positive to -30 mV with characteristics typical of L-type Ca2+currents: when using 10 m m Ba2+, maximal inward current and inactivation time constant (τ) increased; the L-type Ca2+channel blocker nifedipine (1 μm) reduced and the L-type Ca2+channel agonist BayK8644 (5 μm) enhanced maximal inward current.Acetylcholine (100 μm) and carbachol (1 μm) led to an increase in inward Ba2+current whereas application of the tyrosine kinase inhibitors genistein (50 μm) and lavendustin A (20 μm) resulted in a decrease in inward current. The application of daidzein (10 μm), an inactive analog of genistein had no effect. Depolarization of the cells with 135 m m K+or direct stimulation of L-type channels by application of BayK 8644 led to an increase in [Ca2+]i. Carbachol (1 μm) induced an increase in [Ca2+]iwhich was decreased by application of the tyrosine kinase inhibitor genistein (50 μm). We conclude that HTM and BTM cells express voltage-dependent L-type Ca2+channels that influence intracellular Ca2+concentration and thus may modulate TM contractility. The activity of L-type Ca2+currents is influenced by muscarinic agonists and tyrosine kinases.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
